Purchasing a long arm is not something that you jump right into. Each machine is different, with different feelings in the way it moves, the way it operates, everything about it. You might not like a TinLizzie. It might be too heavy for you or your sister, the controls might not be placed correctly for you. I'm not saying that it's a bad machine, it might just not be the right machine for you. Don't purchase on price alone, if you do you are selling your self short. A long arm is a large investment, although it sounds cavalier, when you are spending that much money, make sure that the machine that you purchase fits you and the way you quilt. I've spent the last 6 months researching long arms, made a decision to purchase a specific machine 3 different time, and then I read a bit more and learn a bit more and everything changes. Unless you have to purchase the machine RIGHT NOW, you owe it to yourself and your sister to test drive every machine in your price range. It's the only way to find a machine that's comfortable for you. One option I see mentioned a lot is a hydraulic lift, does it have a stitch regulator, how easy is it to access the bobbin with a quilt on the machine, and the list can go on and on. You need to make a list of what you want in a machine. While you are at it remember that unless you live in a large urban area with a dealer close by, you'll be doing your own repairs and maintenance on the machine. Are you capable of doing that ? One manufacturer gives you a two day maintenance course when you purchase their machine.
Bet you didn't realize what you are thinking about getting into was so complicated, did you ? From what I've found out you really need to do your homework. Take a look at this site
http://mqresource.com/forum/index.php?act=idx
It's one of the best resources for long arm users I've found. It's largely commercial users but there's bunches of good info there. Look for a post about Adam and his trials and tribulations with purchasing a machine on price alone, it's an interesting read.