Antec NEO ECO 400C 400W Continuous Power ATX12V 2.3 / EPS12V 80 PLUS Certified Active PFC Power Supply $29.99 AC + FS from Newegg

Ended up buying this - thanks!

It's hard to find a lot of reviews on the 400C, but it's the same design as the Seasonic S12II series which makes it an excellent PSU, especially at this price. It's also only 150mm deep so it'll be a comfortable fit for my HTPC build (not usually a consideration).

Ripple suppression is excellent. The fan is a quality ball bearing ADDA instead of the cheaper sleeve bearings (Yate Loon) found on other units, which make me nervous since sleeve bearing fans shouldn't be mounted horizontally. Ought to be very quiet like the S12II. Efficiency in the 84% range or so - the S12II platform is rated 80 Plus Bronze, but for some reason these are only rated at 80 Plus. Here's a somewhat informal review: http://forums.guru3d.com/showthread.php?t=317192