The Proofreading Business -- someone has to do it

I am slowly starting a proofreading business. Right now, it will only be digital (preferably in Word format) and won't involve 'hard copy' at all. This is mostly because I really do not have a place to work on a hard copy at home :)

I have finally come up with some rates..... took a little bit of looking, and I really hope that I'm within the realm of reasonable.... Anyway, here are the rates:

Quick Proofing
If your work is already complete, but you're nervous and would like to make sure there are no errors:

•$1.95/page for corrected file copy

Basic Proofreading
Includes proofing for spelling mistakes, typos, punctuation,
capitalization errors, and awkward grammar.

•$2.50/page for corrected file copy

Extended Proofreading / Line-by-Line Copyediting
Includes everything that comes with the basic service plus proofing
for general structure, clarity, sense, word choice, redundancies, and
inconsistencies in narrative voice.

•$3.50/page for corrected file copy

In the case of this last one, I would mark a copy in red and seek
approval before making changes.

Standard page is 250 words (divide total word count by 250 to get
number of pages). If there is a "rush" there would be an extra charge
determined on a job-by-job basis 

I'm thinking I should have a 'minimum charge' but I'm unsure of what it should be.  Suggestions are welcome.

Payment accepted through PayPal
 I can be contacted at cyfarwedd@gmail.com