As much I would love to play the games in the vita because I really do. It would be cheaper just to buy the UMDs with EMS than the digital downloads for me. Point cards are pure murder if you dont live in Japan.
It mostly depends where you get the points from. Of course, if you have someone vacationing in Japan to buy them for you, it's probably cheaper. That said, I ironically paid more to buy a copy of Wandering Star from Playasia rather than downloading it. I paid $72 dollars for PSN points from Japan Codes to download Missing Moon and with that (also wanted to download a DLC song as well for my Let's Play of Idolmaster 2, which is why I bought the points too), I think it came about a few dollars cheaper providing that you can actually find a copy of it since that is out of print.
Still, I think you can still buy a significantly cheaper download copy (about 500-700 yen) if you have a physical one through the UMD Passport program. Not sure if it worked because it wouldn't recognize my copy of Wandering Star, probably because the cheaper version is out... but whatever.