Advice on spare keyless remote

Hi everyone,

I'd like to get a spare remote for my 2003 MX-5. It is a 3-button model (lock, unlock, boot). The Mazda ones are quite expensive, but there seem to be many aftermarket models. I guess some are better than others, so any piece of advice will be appreciated. Also, are they straightforward to program?

Thanks for your help,

Alain