Hi,
I'd advise against the Wren. It was my first concertina, and I think other companies offer a better product for the price. Stagi and Rochelle look good, but I haven't tried them.
My second concertina was/is a Baritone C/G by Morse (Button Box) and it's incredible! I'd highly recommend them, but it might be out of your price range.
Keep in mind that in many cases you can sell a good used instrument for the same price you purchased it, provided you didn't use it much.
All the best,
Scott.