Need cheap prebuilt PC to uprgrade

[LampGoat]

Hi, i recently bought a GTX 750Ti (ASUS) for $50 bc it was a really good deal. But now that i check MY prebuilt pc that i bought like 4 years ago, I realize it's basically a laptop inside a desktop tower (HP p2-1334) and there are absolutely no upgrade paths for me to take with that.
I don't have enough money to go and buy every single thing separately (only things I need at this point is a motherboard, CPU [like an i3-450 or an i5-850], PSU, and of course a case. I've seen a few Dell Optiplex computers but most of them have a single slot video card on the case; hence not allowing the GTX 750TI. My question is: are there any prebuilt PCs that I should look out for? My budget is $100.

 

[Math Geek]

you can look at newegg for their refurbished office pc's. lots of them with i5's on a cheap mobo and usually a lot of ram. it'l have a hdd and such as well since it is a complete system. not sure about $100 but they should play nicely with the 750ti as it takes little power. does the 750ti you bought use any extra power?? 6-pin or 8-pin?? or is it just powered by the slot?

the psu is usually rather weak in these but it would handle a 750ti with no extra power needs.