do you have a link to the ebay store?If you only have one key with the transponder, just buy a $120 or so key programmer, blank key and transponder from ebay, then program it yourself. Then sell the programmer on ebay for $10 less. I got my two spare keys made for less than $30 that way (including cutting the key at the locksmith). I remember the programmer I got was from obdstore (F100) in 2018.
If the locksmith charges you over $10 for the key, they are scamming you.
Please redirect your question to the vender for any form of guarantee. I am just a user and the old model has worked for me in the past. I am just waiting for the blank keys and chips to be delivered to try it on my new Mazda 5.Is there any guarantee that it will be reliable?