Homer Simpson: you can probably call your credit card company and explain your situation. They will raise your limit most likely.
digme: the deal isn't all that bad. Of course the larger the purchase, the more mercata money you use. Personally I'd just sign up and take a look around... Unless it costs money. Price matching is covered in quite a few threads here...
Basically, you walk into the store, go get the merchandise, and walk up to the customer service desk. There you explain that you'd like to pricematch an item (note that the store has to have a pricematch policy). Then they'll try to get out of it by saying it isn't the same item, the price is higher, etc. Calling the competing store for the price is normal. To help your case you can purchase the item at the other store and then return it - now you have a receipt that you can use to prove that the price you say it should be is correct. You may have to ask for the manager if the customer service person isn't being very helpful.
I'm sure I missed a few details so anyone who feels like plugging the holes, go for it!