So, how do you do it? How can you afford to drop 2g's and still survive?
Oh... Lots of things:
1) Budgeting. When the year starts I know exactly how much money I can spend on computers and gadgets. For me that's about $2k so for the 27" iMac I need to sell some stuff (20" iMac, first gen 17" MBP) which should raise about $1k and make the numbers work. (already bought an iPad this year, -$500) That leaves me with enough for an SSD or a white iPhone 4 if Apple ever manages to ship them.
2) Selling your old stuff while it still has value is very important. There's a pretty quick drop off from say 75% original price to 50% original price. With Macs they tend to hover around 40-50% for quite a while. I sold an original white MacBook last year for $450.
3) Watch out for avoidable expenses. Change your own oil, buy stuff you use a lot in bulk, don't order the most expensive stuff on the menu, avoid stupid fee's and charges with your bank/credit card/etc, be good to the stuff you own so it lasts, slow down a little big on the highway to get better gas milage, etc, etc. All this stuff really adds up by the end of the year.
4) Don't get too many expensive hobbies. Computers/gadgets are my big one. Everything else I enjoy is comparatively cheap.
5) Don't pay for cable/satellite TV. You can save $1-2k a year on this usually. You're not missing much.
6) Develop an enjoyment of water. It's cheap (or free) and healthy. $1-2 worth of unhealthy drinks a day really adds up by the end of the year. (again, buy in bulk if you must)
7) Don't turn down a free meal.
8) Get drunk before you go out. (major savings here)
9) Don't have kids (seriously)
10) Old news papers and magazines can replace expensive toilet paper. It really adds up. (alright that one is a joke)