Mattress?

So, Mark and I went shopping at Ikea for a bed (in our little Honda lol). We found one and bought it in a King size (they were out of Queen). My wonderful mom wanted to go shopping, so she took us to pick it up. But, we are thinking it will be WAY too big for our Queen mattress. Here is a picture of it.

We haven't had time to set it up yet though. Our only free time is Tues/Weds since neither of us have to work. So, it should get set up on Tuesday, and we will see how much too big it is for our mattress. We have been browsing Craigslist for King size mattresses in the mean time. If anyone knows where we can get a King mattress under $200 let us know!!! I really want a memory foam mattress and found some on Ebay, but I don't know if I can trust them. I found a few used memory foam mattresses on craigslist for $500+, but that is well over our price limit... lol There is a place in Midland that has cheap mattresses, but that is WAY too far for just a bed lol... We would be better off finding a more expensive one here with the cost in gas to get there! Geez...

Again, if you know where I can get a good KING mattress under $200 let me know! We may just buy a really cheap, crappy one and get a memory foam topper for it. Keep your eye out for us! Thanks!