I'm in the same boat, my provisional runs out in April, and am wondering what to do. I lodged the provisional myself and save a few $K.
Here's my current thinking, over the course of the patent it will cost around $250K or more over 20 years. If I had $250K now would I spend it on my patent? Right now, I'd much rather have the $250K so from the good investment point of view - the answer is no.
What about the possibility of someone else patenting it? Well since the provisional has been lodged I don't think that's possible once the product is in the public domain, so from that angle I'm safe.
Can someone reverse engineer the patented bit? If they can what investment would they have to make to build a competing product, i.e. are there any other bits that aren't in the patent but are hard / risky. If a competitor has to make a large investment to catch up to you, then they may be better off just buying your company.
Will this be the only invention you ever make? If you're young and you've got something patentable already then most likely it wont be your last. It's not my first and I know it's not my last, once an inventor - always an inventor.
Someone mentioned it's good to have a patent on the resume, from my experience it can scare the hell out of some employers, so that's a bit of a 2 edged sword.
Perhaps the bit that get's stuck the most in my craw is that I'd be paying thousands of dollars to some patent guys who sit in a nice office and wear expensive suits and silk ties while I'm busting a gut making a startup, it's petty I know but it really gives me pause. I figure if they have all that money then there is a lot of cream on top of the patent industry.
The other thing to consider is how much time it takes to write a patent application. I know for myself it was a few weeks to actually write the provisional (and this was time well spent as I defined what I'd actually invented and found out a few other things along the way). It also takes time to work with the patent guys, don't underestimate this. You have to have meetings, review there work, make changes and so on.
I figure if my products successful, then by the time it reaches the point where I had to worry about patent infringements and so on I will have made more than enough money for me and I'll be doing this to grow to the next step.It usually takes about 5 years for a patent to be approved, 5 years is a long time in software.
The conclusion I've come to is it's a big boys game, and if you want to play then you have to pony up the cash, either get the cash or get investors who have the cash otherwise do what you can to protect yourself and move on. Of course it depends totally on what you're patenting - if it's a major breakthrough then it may be worth getting investors. If it's incremental then execution probably matters way more than whether or not you have a patent.
hth.