+1 to what John and Kurt said. It's a great place to have space to work on your bike, especially if you're like me and live in a small apartment. I also like donating my spare stuff to them.
To use the space you either have to pay a day-use fee ($6) or become a member ($50-$100 for a year, sliding scale depending on what you can pay). Any of the classes come with a membership, which is how I became a member earlier this year. I think you have to pay an extra $40 to get digging rights to comb through their spare parts to build a bike, but I have no idea if that fee applies if you have all of the parts for a bike already and just need the space to assemble it.
My experience with the Bike Kitchen has been great -- I'd recommend it for anyone looking to do maintenance and learn. They sell new parts at cost, seeing people from different backgrounds working on bikes is cool, and the staff does what they can to lower barriers to access (nobody is turned away for lack of funds, you can also become a member or get digging rights by volunteering). Check it out if you're in the area.