PayPal and eBay help.

Never used Ebay cards but I would guess you can use them to buy whatever you want on Ebay. What other questions do you have?

You're kind of in a tricky situation and going to have to see what you can do as your own adventure in seeing what is possible. Paypal is normally/always/has to be? linked to a bank account. It'll make two small deposits you have to verify, and then it will automatically withdraw them. Second, you can put credit cards on your account, but you can't split payments between credit cards. The only split payment you can do is one via paypal balance (money you receive either via selling stuff, or funding directly from your checking account, and/or possibly via adding gift cards(...?) and credit cards. So you can only split between your available paypal balance AND your credit card (or your bank account, if you want to get technical, but you said you don't want to do that).

Your other payment option is via directly paying via credit card (or gift card?) to the seller, if they accept that form of payment (? I'm not sure if every seller has to accept that method now or not, and I don't know if it applies to Canada). It's a new thing to US ebay that is less than a year old. You might be able to split payments between credit cards and/or gift cards, but I heavily doubt it.

Ideally you're going to want to do 1 of 2 things.

1) Have enough money on a single payment method so that you don't have to split it. You can either do this through ebay's website or via Paypal.
2) Have a bunch of paypal account balance, and a credit card to pay the rest. You would only be able to do this via Paypal.

Also, if you don't already have a paypal account, you're going to have to go through a verification period, and it's going to take some time (days) to get it authorized and set up.

Also #2, ebay sellers pretty much hate selling to new people, because sometimes paypal payments only come through in the form of an e-check that takes a week to verify and cash. Therefore, it will delay them sending you what you won. I hate selling to new ebay users because of that. And you're most likely guaranteed to have that annoying BS wait because of the amount you're saying you're going to spend. However, if you fund your paypal balance directly (by selling stuff on ebay and never withdrawing it and transferring the money to your bank account), I'm pretty sure paypal balance payments don't have a delay and are instantaneous. 

Eventually, when you've gotten enough feedback and had enough paypal account activity, you end up being able to instantly send money via your paypal balance, credit cards, or bank account, without any sort of delay.

timone317 might have some advice since he used to use gift cards on ebay I think.

Oh, also, signing up for your ebay account, I am pretty sure it absolutely has to be linked to a credit card at minimum. A gift card won't work I am pretty sure. I don't recall if a bank account has to be assigned to it or not.

And on an unrelated note, I think you should be more patient when looking for King Cold. $550 USD is too much for him, by a lot. That one on ebay currently is missing his extra hands and has paint damage on the tail. I know the wire in his tail ends before the tip of the gray part, but I would guess the owner was bending the gray part in half or having some other figure grasp the tip of his tail and swinging KC around by his tail playing with him. To me (a biased perspective), that KC is not worth close to $550.  This ok looking one missing one hand and with a crack in his shoulder armor sold at the end of June  sold for $419 including shipping.  This one with some paint damage, a missing cape, and missing extra hands sold for $357.85. This small group that included KC, Cyborg Frieza, and purple haired SS Trunks sold for $303.78 and KC had his cape and was missing 2 hands.

So I would just be patient, wait, and look every day for new ones listed. I wouldn't be afraid of one missing the cape either. There's nothing special about it if you know someone with a sewing machine. You could make your own cape and it wouldn't have to have the white tag on it, that only a fool (at this point) would cut off of it. Technically, the cape is inaccurate to his character design anyway. His cape in the anime is extremely dark blue (or black) with red on the inside. It's also pinned to the front and top of his armor with some gold rivets, not held on with elastic. You could custom make a cape, using some glue dots to temporarily hold it onto the figure, and it would look so much better than the black cape with elastic that Jakks made. You could also make a second one in solid red if you wanted to make him look like he was from the DB Super Broly movie as well.

Lol, and now I'm really having fun with alternate ideas. If you really wanted to save money and have some creativity, you could buy a Frieza form 2 figure/statue and customize it into KC. You'd save hundreds of dollars, even after buying acrylic craft paint from Hobby Lobby/Michaels and ordering Aves Apoxie Sculpt online to do the custom sculpting. You could get this bootleg Scultures Frieza or this authentic one. Or... you could get Demoniacal Fit Captain Ginyu, a WCF King Cold head (I suppose it would scale well), and sculpt the other details. If you're 30 years old and do all this 3D design stuff, you are probably creative and patient enough to do a really good job sculpting and painting. 

If I was going to spend $550 on a King Cold, I'd get this enormous statue, because it's surely better quality than a Jakks King Cold that originally retailed for around $16 in a 2 pack with Trunks.