+1 (well, +2) on what several folks have already suggested -
Do try to find someplace to take an intro/certification class so you are familiar with operating a longarm. The class I took included practicing on a couple of charity quilts. This was HUGE towards me being comfortable test-driving machines.
Then try, try, try. Try every one that you can that is in your price range (and maybe a little above in case you can find a gently used one). Pay attention to feel and sound - are there ones that grate on your nerves? There were for me.
It's a big investment so take your time and find the one that makes you smile when you use it.
Michelle