I wouldn't bother to be honest... even the legal ones are renowned for their terrible build quality and poor materials, not to mention the fact that half the time they come in a crate with some (albeit minor) assemblage required, often with extra hidden costs such as registration and various duties. Although they are still pretty cheap, you'll also have a terrible time trying to sell it on second hand- and I guess if you're looking for a 125 you won't be planning on keeping it for that long, so it's worth taking this into account as well.
Far better in my opinion would be to take your A1 and get anything up to 33bph instead of a 125, which gives you far more options. If however you really want to continue riding with plates get a cheap, older but ultimately more reliable 125 made by one of the more reputable companies- something like a late 90s Yamaha DT125, Suzuki DR125, Honda XR125 etc. will do you well.