Just a couple of points to add - one piece of advice and a general observation for you to consider.
I have a GPS which I use as a backup only. This is a non aviation one, which cost just under £100 when bought new about 3 years ago. (That's about $180 at current rates of exchange). No moving map at all. Bar Shakers advice regarding turning it on before you fly is good. I once did a 45 minute flight with the unit sat atop the glareshield and not managing to acquire the satellites at all. I'd forgotten to turn it on before I took off. (That was in a tired old Warrior cruising at 95kts). To be fair, an instructor who has an identical GPS tells me that he's been able to turn his on and acquire the satellites in flight, no problem and that in a faster aircraft. The lesson may well be to try out your set and see whether it'll reliably acquire in flight. If not, turn it on before you go.
One of the other aircraft I fly has a full moving map display. The refresh rate with this is such that I find it more of a distraction than a help. Also, the way this is set up doesn't much help either, as the mapping turns to give the direction of travel at the top. Accordingly, if you're going south, then south is to the top of the display which I find disconcerting. As it's a hired aircraft used by many, I can't really play with the settings without inconveniencing others.
It may be worthwhile borrowing a GPS from a friend and see how you get on with it rather than pay a large sum of money and find you'd have been better off with a much cheaper, non aviation GPS, which will tell you where you are, what direction you're going in and how fast.
P