First build questions

[Monetizer]

So I was wondering if I want to connect using an ethernet cable will I need to get a network card? What is a good price for one? Also what is a fair price for a 5850? Also does it matter how many gigabytes a GFX card is?

[HellDiverUK]

You'll have to get a network card if the motherboard you're using doesn't have one.  But, I haven't seen a motherboard in about 10 years that hasn't.  You can get USB ethernet cards which are good enough for mining. 

A good price is free.

Fair price for a 5850 is as little as you can, like anything.  Check eBay and see what they're going for.  Use the watch list, so you can see what they sell for.

GPU RAM, doesn't really matter.  Most cards are 1GB at least.  I haven't seen any difference in using a 2GB card over a 1GB one.

[Monetizer]

Thanks! I think the motherboard/ethernet will do fine with an open rig. Also Is around 70-100 reasonable (Thats what they go for here I think) and how do I know if a GPU is voltage locked?