I thought I just had to have a 12" X 18" one...I still use my table top ironing board for just about everything. At 20+ dollars they aren't worth the price of $1.00 per inch which is what they average out to.
Oh and one more thing, it's very easy to forget that you should be ironing on one side and cutting on the other...hey, accidents happen but don't ask me how I know that. lol.