The 18 month plans are no interest or I wouldn't bother.
The bass I'm looking at costs $750, and over 18 months that comes out to about $42/month. I can handle that.
Go for it if you can 100% guarantee that you will have it paid in full before the 0% is over.
My guess is the interest rate will be 19% or higher once t kicks in. Don't go there.