Help me GAF! I'm going through another one of my "should I buy a Vita now or wait?" moments.
Hey. I was in kind of a similar situation to you a couple of weeks back. I decided to cave when I saw Amazon doing a deal of the WiFi, Rayman and a 4gb card for £185 brand new. I thought that was pretty reasonable so I dropped the cash, but they're not doing that bundle right now unfortunately. Places like CeX sell used ones for £160-70, but I don't know the condition of them, and neither will you until you get it in your hands. You could ask in store, I guess.
I have no idea about Sony's price plans so I can't really comment on whether you should wait or not for a price drop.
It looks like you have a pretty good list of games you want there. Do you own a PSP, or did you just download 3rd Birthday/VC2 because you knew that at some point, you'd play them on a handheld? I would probably say if you already owned a PSP at some point and played it a fair bit, you might want to wait until you see a price you're happy with. If you didn't, and you have some more PSP games you'd like to play, I'd just jump and get a Vita. You're basically getting a PSP for free, and they're like, what, £50 now? That was a big attraction for me, at least, I considered it like getting a Vita for £130
If you don't handheld game a lot then you should get good life out of stuff like GR, UGA etc until P4G and Ragnarok come around.
As for memory cards, again, depends on what your PSP plans are, and on your digital/physical preferences. If you want to have a few PSP games on there, I'd recommend an 8 or 16gb card, just so you can have that flexibility, but if you're the type of gamer that only wants to play a couple of games at a time, a 4gb would actually be fine if your Vita games are all physical copies, and the only problem would be the hassle of removing a PSP title when you're finished with it and putting something else on. However if you're going to play more than say, 4 titles at a time, you should get an 8gb, probably.
It's a great little piece of tech and I love it, but yeah.. I wish there were more Vita titles. For now the PSP games are doing me fine.