Hi J.!!
I used one at an all day crop and was addicted afterwards. I had a bunch of pages, but wanted special titles and accents that I just couldn't find - until I got the cricut. I was able to really make simple pages look complete with my cricut titles.
I got the expressions one - the big one, thinking like the other respondent that it would help with children's projects. A friend of mine has one too and she said that if you buy 2 of the bigger mats and cut them down, they are cheaper than buying the 12 x 12s individually.
I got my expressions at www.customcrops.com. They had the best price, free shipping and get on their email list because they will announce sales - all cartridges 38.00 - that is when I buy them. But to get the best price on the machine, you have to see what it comes with. Some places will charge 300 or 320 for the machine and a cartridge, a mat, etc. Some will charge you less, but you are only getting the machine. Just make sure that when you compare the prices, you are comparing apples to apples. Also, some that are priced higher might come with more cartridges, but really make sure that you will use the cartridges that are being added in - some times it might be worth it and some times not.
Please let me know if you have any other questions. Good Luck.
K.