Is it worth working for someone else to learn from them or is it better to go out on your own?

This is a tuff one! As an entrepreneur, you will never be truly happy working for someone else. Not to say there is anything wrong with working for another company, it is just that entrepreneurs have a drive to innovate the process and shake up the market that just does not jive well with working for another person. Reading through your question, I would first suggest that you really think over the question at hand and make sure that your recent set back in business is not the driving factor to work for someone else. I have now started 9 businesses from scratch and of those nine, one of them was a failure. The failure gave me pause before I started another business, 6 months to be exact, I began to second guess myself. Once I moved though that by recognizing the driving factor, I was able to jump back out to my natural abilities again.
With this said, I will say that I learned many of the skills of consulting and business through my 2.5 years working for a consulting firm owned by someone else before I started my life as an entrepreneur. There is safety in learning while being paid! The other benefit to working under another developer is to gain access to His network of individuals and vendors while gaining the creditability that he holds. While working for him, you will be building your own credibility in the field so that when you step out, you will have instant credibility for your own business.

Please let me know if I can be of more help, I would welcome the opportunity to talk by phone with you to let you know how I was able to keep an open communication about my intentions of going out on my own while working for my soon-to-be competitors.

Is this a field you want to learn in?

If so, it's a good opportunity to learn how deals are made...provided your personalities are a fit.

Compared to climbing the greasy pole of jobs, this could easily save you 10 - 15 years.

It's a lot easier to make things happen once you see the idea in action. Figuring things out on your own takes trial and error, and pain. This could be a good shortcut.

All the above.

I take any money, any time... well, there are some exceptions. I tend to fire problem clients, after a few warnings.

If you have an opportunity to work for someone, who will pay you a truckload of cash, take the cash + work other projects on the side.