I've got the Blackline 200, rather than the 250. Its a perfectly decent welder for the price. Used it for making myself a new trailer a few years back. Doesn't see a lot of use but handy to have.
I think the BlackLine MIG welder was available in a higher power rating, but at the moment both the Rally Design Ltd. website and their eBay listings only offer the 200A model. A cheaper and better alternative is the Bimson Power version:
The Bimson Power BP-MIG200AMI is a powerful and portable 3-in-1 welder, built for both professional and home users who demand flexibility and reliability.
www.bimsonpower.com
It is the same machine, with the same 200A rating, but the advantage of a simple torch polarity swap to use gasless flux-core wire.