As of I believe it was Oct 2012 they changed the minimum speed to 8kts for yachts. After you pay all the fees for registration, transit, inspections (your boat has to undergo inspection to make sure it meets minimum equipment requirements), tolls, etc., you'll wait 8-12 days before you get to make passage. When your time comes you'll probably go through with a smaller commercial boat. If you can't maintain speed to make lockage with the boat you're assigned with you're going to pay extra for transit pilot delays (commercial boats have to have a canal transit pilot), and a whole bunch of other stuff that totals up to about $900 (besides the above).
You will be required to maintain your transit time, regardless of weather. If you have to pay for a Canal tug to make your allotted transit time it's going to cost you about $200 an hour for a 28 foot boat.
You have to have a Canal Advisor onboard and you have to pay him and feed him. If he has to order a meal box because you don't feed him it costs like $30 bucks plus a $185 delivery fee for ONE meal. You're also going to need crew - four line handlers. You can hire them too - they'll be there waiting to get their piece of the action (meaning money). And you have to pay for their return ticket to back where you picked them up from.
You're going to have to rent tires from a local marina to protect the sides of your boat. And you have to arrange for return of your rented tires to back who you got them from. If you don't have four 125 foot x 7/8" lines on the boat you have to rent those too. Same deal as the tires - you have to make arrangements to get them back to their rightful owner after you make passage.
In the end there's a whole bunch of people from the agent that you're going to pay about $800 to handle the paperwork (unless you're fluent in Spanish and know how to do it yourself) to the people that will take care of getting your rented tires and lines back, that make money off a passage though the Panama Canal. If you got money to burn it will be a neat experience to say you have done it. If you're on a budget - look for a different way to get to the other side.
If you do decide to do it it would be a good idea to just get an anchorage for your boat and hire on as a linehandler so you can learn what's required before you try it. Private yachts that have never done it usually go through with a "buddy boat" and they crew each other as linehandlers and each yacht makes its passage at the allotted time.
My wife and I crewed on a friend's yacht that made passage thru the canal once. We sailed with them from San Andres to Tobago and Rio De Janeiro, then flew home. They were in Rio for 3 weeks and we flew back and crewed to get them though the canal so they could sail to Hawaii. After seeing all that's required we would never do it with our boat. I'd sail the other way around the planet to get to the other side instead. We're happy with the Caribbean. Have no desire to get to Hawaii. And Panama is the last place on earth that we're in a hurry to get back to
Totally off-topic, but hope that all helps. I think I'd find somebody with a sailboat trailer and a one-ton diesel pickup. Rig up an A-frame to unstep and step your mast yourself, and just get the boat to the Gulf so you can have fun. If you don't have the money for the Canal it's not going to be fun because you'll be broke when you get to the other side