$75 for a 32GB is way too much. There is a 8GB for $18, uhmm, can I erase games and then download them again?

lol fixed

yes but you lose your save, or you can move them to a PS3 or PC to save redownloading games all the time and keep the save, or upload the save to the cloud via PS+

I think I might not get PS+, but I wouldn't mind moving them to my PS3, or the PC.

Ok, thanks for the info.

Uhmm, but I just saw this:

Is 4GB too small?

I will pay $10,000 for an 18GB Vita memory card.

yes but i won't recommend it 

For digital, yeah.  If you're only going to use the memory card for your save data, and buy retail, then it's good enough.  If you're going to buy digital you'll be able to have one or  two Vita games on there before you need more room.

Right now Amazon and PSN has PS+ for $30 for a year.  If you're thinking about getting the Amazon Vita for $180, then I'd recommend to just get the Newegg Vita for $150, $30 PS+, and then a memory card.  You'll get a lot of games free with PS+.  If you have a PS3 and Vita you'll get five free games per month and the value is much better.  If you don't have a PS3, then go here https://store.sonyentertainmentnetwork.com/#!/en-us/home/main.  This way you can purchase all free PS+ for PS3 incase you get one later. 

I do have a PS3, and I'm interested in digital games. But I'm not totally sold on PS+, and then I'd also need a big memory card.

Puff, still, thanks all for the info.

Well.  Here is what you got for one year of PS+ starting at E3 2012 last year to E3 2013 this year. While you can't play the games without being subscribed to PS+, you never lose the games that are on your PS+, so subscribe again and they'll be available while being able to get more games.

It's a great service.  Well worth paying the $30 it costs now, even $50 if it wasn't on sale.  For the cost of one game, you get 60.  The free games you can get now(if you live in US,) are Hotline Miami(PS3/Vita,) Soul Sacrifice, Ibb and Obb, Contrast, Resogun, Binary Domain, Dragons Dogma Dark Arisen, Poker Night 2, Shadow of the Colossus, Ico, Galaga Legions, Zen Pinball 2 Star Wars tables(PS3/Vita,) Bit Trip Runner 2, Uncharted 3 single player, XCOM Enemy Unknown, LBP Karting, Oddworld Stranger's Wrath, Wipeout 2048, Uncharted Golden Abyss, and Gravity Rush.

So for $30 y ou can already download four retail Vita games, several Vita PSN games, and retail and PSN games for the PS3.  Just trying to sell you on it for you to purchase it ASAP because next month you won't be able to purchase five of the games for free and you'll have lost out if you decide to eventually get it.  They rarely offer the same game twice, infact they haven't since E3 2012 except when they offer  the PS3 version by itself then later the Vita version.     

Amazon has the 8gb vita memory cards for $9.99 (currently out of stock but you can still order them for when they are back in stock).

http://www.amazon.com/gp/offer-listing/B006JKAS6G/ref=dp_olp_new?ie=UTF8&condition=new