It's a small startup with 12 workers, 1 founder, bootstrapped. Started 11 month ago. Least Profitable Month: 7000$ Profit Most profitable month: 32.700$ Profit
With growth next year Potential monthly profit: 50 - 100.000$ Profit (my calculations)
In simple terms, the value will be some multiple of profit. The best blue chip companies get about 10x plus dividend. You are not a secure bet so you might get 3x to as little as 1x. Plus someone might have to manage the business which eats into profit.
But, the best growth companies could get 20, 30, 50x+. So your job is to argue growth.
Ultimately however, you shouldn't calculate a value. The above should just determine a minimum. You need to figure out what your business is worth to the acquirer.
You need to take a ton of factors into account before you can ask for any advice. You could also try your luck at listing it on Flippa.com or something similar.
That said, determine the earnings (if you can) and set a P/E of at least 30.
Let's say your earnings in 2012 were 1 million, 30 million sounds like a good price for the company, keep in mind that value is a measure of interest or the need for something.