There "is" an alternative method. Unfortunately, this can be a double-edged sword sometimes... in that... it can be a
good thing or it can be a
bad thing.
I use to work for one of the largest key blank manufacturer's in North America, but the KEY word here is...
used too. Those a**holes laid me off this past Feb., with 43 other people, but that's another issue.
In any case, I'll tell you what I
can remember, which may or may not help. But at least it'll give you some place to start.

There is a way to get some vehicles to accept a new TRANSPONDER key without an expensive trip to the dealer. Keep in mind I said...
SOME vehicles. And it can also vary from one manufacuturer to another as well as, from one model to another. Even then, some vehicles just "can't" be done without a trip to the dealer.
The process is known [in the industry] as
"flashing" the ecu. What this does, is erase or clear the ecu (i.e. computer in the vehicle), of any existing transponder key info and allows for a "new" key to be programed into it. And yes, you can add keys as well, but again...
it depends on the "make" and "model"... and sometimes... even the year. The best part is, it can be done by a qualified independent locksmith, who specailizes in transponder key technology. Depending on where you live, you'll just have to do a little leg work and ask your local locksmith(s) if they have the technology. There's also a hand-held device which was designed by the company I "worked" for (called a TD3AII) which is basically an industry standard, and it actually plugs into the port on your vehicle under the dash and allows the locksmith to do the work right at your car.

Pretty neat stuff.
So, my advice... at this point... would be to contact a few local independent locksmiths and ask a few questions.
Hope this helps... a little... anyway.
