Building an i7 rig isn't a cheap proposition from the get go, so if money is an issue, but you will not settle for Core 2 or Phenom II, then among these 10 boards, all well under 300 dollars, will give you some options to choose from. Varying levels of features abound among these mobos, from the nearly stripped down MSI X58 Pro to the bells and whistles galore of the Gigabyte UD4P, you should be able to find a good fit for your needs in this list. If money is no concern, then this list isn't for you. If trying to get an i7 on a budget describes you, then this list IS for you.
1. MSI X58 Pro $169.99 (MIR, Newegg)
2. Zotac X58SLI-A-E $174.99 (MIR, Newegg)
3. Gigabyte EX58-UD3R $186.81 (Ewiz)
4. MSI X58 Platinum SLI $209.10 (Ewiz)
5. ECS X58B-A $211.47 (mir, Ncixus.com)
6. DFI Lanparty JR X58-T3H6 $214.20 (Ewiz)
7. Gigabyte EX58-DS4 $215.44 (discounted until 3/3, Ncixus.com)
8. Asus P6T $224.40 (Ewiz)
9. DFI LP DK X58-T3eH6 $229.50 (Ewiz)
10. Biostar X58 T-Power $231.31 (Ewiz)
Using the Zotac X58SLI-A-E motherboard, This 3Gb G.Skill DDR3 1600mhz kit for $60 bucks and a Core i7 920 for $288.99, the core components are now down to under 530 dollars before shipping (not counting MC i7 920 deals since you have to live close to one to benefit).
Edit: List updated
1. MSI X58 Pro $169.99 (MIR, Newegg)
2. Zotac X58SLI-A-E $174.99 (MIR, Newegg)
3. Gigabyte EX58-UD3R $186.81 (Ewiz)
4. MSI X58 Platinum SLI $209.10 (Ewiz)
5. ECS X58B-A $211.47 (mir, Ncixus.com)
6. DFI Lanparty JR X58-T3H6 $214.20 (Ewiz)
7. Gigabyte EX58-DS4 $215.44 (discounted until 3/3, Ncixus.com)
8. Asus P6T $224.40 (Ewiz)
9. DFI LP DK X58-T3eH6 $229.50 (Ewiz)
10. Biostar X58 T-Power $231.31 (Ewiz)
Using the Zotac X58SLI-A-E motherboard, This 3Gb G.Skill DDR3 1600mhz kit for $60 bucks and a Core i7 920 for $288.99, the core components are now down to under 530 dollars before shipping (not counting MC i7 920 deals since you have to live close to one to benefit).
Edit: List updated