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#11
Your stock unit is made by FSP, which is usually a pretty good brand.
You shouldn't have to spend over 60 to 100 bucks for a high quality standard ATX unit with say 450 to 600 watts somewhere.
If you aren't in a hurry, you can probably pick up a good choice on sale within 30 days.
Try to get modular or semi-modular.
Get the dimensions from the manufacturer and compare to your existing. They don't have to match exactly, but you have to ensure that if the new PSU is say 7 inches long and the existing is 6.5, that there is nothing in the way that would prevent the 7 inch PSU from fitting in the available space.
Newegg.com and Amazon.com are 2 good sources with plenty of choices.
Here's a few good choices:
Full Modular, 500W - 599W, 400W - 499W, Newegg, XFX, Power Supplies, Power Supplies, Components - Newegg.com
EVGA 220-GS-0550-V1 80 PLUS GOLD 550 W ECO Mode Fully Modular NVIDIA SLI Ready and Crossfire Support Super Silent Continuous Power Supply - Newegg.com
EVGA 220-G2-0550-Y1 80 PLUS GOLD 550W ECO Mode Fully Modular NVIDIA SLI Ready and Crossfire Support Continuous Power Supply - Newegg.com
CORSAIR RMx RM550X 550W ATX12V / EPS12V 80 PLUS GOLD Certified Full Modular Power Supply - Newegg.com
all of the above are fully modular
the Seasonic below is semi-modular
SeaSonic G Series SSR-550RM 550W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS GOLD Certified Modular Active PFC Power Supply - Newegg.com
Any of the above should be fine, but check the measurements. You might compare the above Newegg prices for the exact same model at Amazon. They might vary by 10 bucks.