like you, I'd bought one of those Powercolor 9800SE's hoping it would soft-mod into a Pro ($119 price tag tipped me off, but I could be wrong....) mine didn't, but it did overclock, but it couldn't outbench my 64MB 9500np that DID soft-mod , so I RMA'd it and bought my MSI RX9800...
Like KoolAid said, the absolute best option out there for $100 is a 9500pro off of ebay, or if you can find one, a 9500np with 128mb ram in an "L" shaped configuration, and a Red PCB, preferrably made by Sapphire. They are 9700 Pro's with 4 pixel pipelines cut off.
I have to tell you, I had a Visiontek Radeon 9100 64mb that was an excellent card. Like the old geforce 2 gts, it has a 4x2 pixel pipeline architecture, and it really makes a difference if you can't get an 8 pipe card.
Of the choices you've made, I'd stick with a name I know, Sapphire. If you can't get a 9500Pro off ebay, go with the Sapphire 9600Pro from Newegg.
Take a look at this 9600Pro. It looks as if it was built upon a 9700 PCB, note the "L" shaped memory (and the smaller memory chips, possibly BGA, 3.3 ns), and the place where an external power connector would have been. With shipping, it's $11 more, but I think it would be worth considering.Atlantis 9600 Pro
Rig 1: AM2 X2 4850e--MSI K9N Neo V3--2x1gb Mushkin DDR2 800--Sapphire HD4830--Corsair VX450--Acer H213H-Win XP
Rig 2:Athlon X2 7850 Kuma--Biostar 780L--2x1gb Corsair XMS2 DDR2 800--Asus Formula HD4770--Corsair VX450--LG Flatron W2252TQ-Win 7 32-bit Premium