I think PSN is a bit ahead of XBLA in terms of pricing of full retail games. There are a lot that are way over priced but in the past few months I could of bought the following at the following price off PSN (Albeit some were sales prices!):
Darksiders - £9.99
Star Wars: TFU 2 - ~ £8.39
Dante's Inferno + all DLC - £16
Dead Space + all DLC - £16
RDR + Undead Nightmare - £20 (£15 with PS+)
Sly Collection - £10
ICO collection - ~ £12
Splinter Cell Collection - £10
There are lots more too...
I think the main thing you have to remember is that the publishers can't do anything to **** off the retailers. There will be contracts and whatnot saying that when a retailer buys some million copies of a game the publisher can't go and stick it on PSN or XBLA and undercut them for a few years. As we move forward we're seeing the retailers hold less power though - the Vita has every game launch on PSN day and date with retail and once Vita starts having some sales on PSN I reckon we'll see some amazing prices for games like Wipeout, LIttle Deviants, Uncharted : GA etc.
I'm cautiously optimistic about downloadable games in the future. The pricing is getting better every year. PS+ is become absolutely superb value too, once they roll it out on Vita someone like me is gonna be raking it in from my subscription even more so lol.







