Ask HN: What is a reasonable price for the development of this site?

I'm the sole web-developer for a small startup and I created the company's entire product (a website). I may be renegotiating my contract, and I was hoping to get some third party opinions about how much the web development of this site is worth. The site is notescentral.org and is a website for students to share notes.

If any developers out there have a few minutes to kill and wouldn't mind looking over a few of the pages on the site, then giving me an estimate of how much you would charge if you developed this, that would be greatly appreciated. I want to make sure I'm not under/over valuing myself.

Looking over these pages should give you a good ideas of the majority of the capabilities of the site:

notescentral.org

notescentral.org/login (login using username & pw "resume")

notescentral.org/browse

notescentral.org/all

notescentral.org/notes/150

notescentral.org/notes/84

notescentral.org/upload

notescentral.org/rewards

Any opinions would be appreciated