Need help with PSU options.

I got $320 for Christmas to spend how ever I chose. I am getting the 8800GT to replace my 7900GS, however, my current PSU will not power it with my current system (listed below) as my PSU only has 18 amps on the 12v rail.
My max for the 8800GT is $260 (if I wait, I'll find it at that price).

Here are my options:
1) Do nothing and watch my system either refuse to boot, crash or the PSU blow up.
2) Buy the TT Graphic Card power supply for $55
3) Get a new PSU.

Unfortunately, ATM I do not have a lot of money to put towards a new PSU. I know that a solid PSU is paramount, but I do not have the cash for some of the higher end units.

This Seasonic looks good, but only if the discount stays like it is.
Option one is not really an option so that leaves me with options 2 and 3.

If it helps, this video card update will be the last update to this setup since S939 is obsolete. I do not plan on building a new system for at least another 6 months to a year. It depends on how much money I make this summer as to when I build a new one.

Thanks

EDIT:

Since TG didn't like my html links, I have posted them seperate:
http://www.newegg.com/Product/Prod [...] 6817153037
http://www.newegg.com/product/prod [...] 6817151040

Here's the one I'd recommend, rebates to deal with but a good price on an excellent PSU.

http://www.buy.com/prod/Corsair-VX [...] 66485.html