Put it this way, up till I bought a 360 I never bought games that I actually owned a magazine review of (and I keep mags for months), they're too expensive. That's despite the fact that I almost solely buy new so I know I've got media that will last.
That has (very temporarily) changed with the 360, as I traded a lot of the family's excessive crappo DVD collection for Viva Pinata at Blockbuster, then traded more DVDs, Viva Pinata and some other games for Call of Duty 3 and Ice Planet. Also, I got Dead Rising for £25 from the Play sale, and it's still often discussed and in the charts.
Now that's done with, it's back to cheapo games. A game plays no worse for £20 than it does at £40 or £50. Once you get used to staggering your purchases, you've always got something dropping down to a lower price band, IE you're doing what everyone else is doing just with a 6-month delay. Put off buying a new console until the first wave of cheap games comes around (that's what I've done with the 360), then you can take it from there.
360 games bought cheap from Play recently: (£50 each RRP)
Blazing Angels £18
Condemned: Criminal Oranges £15
Rumble Roses XX £15
The Unit £15
Dead Rising £25
Look at Bully/Canis Canem, it's only been a few months and it's £13 new.
Promo versions of games are regularly available on ebay. I bought Siren 2 for the PS2 weeks ago for £3.70, it had only been out a few months, this was a brand new promotional copy in a CD single case. Samurai Jack.. paid about £3 for that. Paid £13 for Atelier Iris: Azoth of Destiny on promo when it was just out, paid the same for Dragon Quest when that had just been released. Why pay more? Only downside to promos is that, obviously, you can't trade them and either have to sell privately or keep them, but at these prices I'll keep em.
I'm currently waiting for Samurai Warriors 2 on the 360 to take a tumble, likewise I'll be snapping up Okami when the price drops off. Give it a try, you'll be amazed at how much further your money goes AND end up with a whopping collection.
Ooh, one last thing, remember to trade your unwanted games sooner rather than later whilst they retain some value, also make sure you SHOP AROUND, one chain of gamestores might have dropped the value of an ageing game whereas another won't have done - if the price is wrong then keep hold of it and try elsewhere.