Looking for a reasonably priced wheelchair with anti-tippers (UK)

Hi all,

I want to get a cheap (ish) wheelchair for daytrips and the like, as I struggle to be out for more than a couple of hours on my crutches.  I'm quite petite, so any wheelchair I have needs to have anti-tippers as I tip a LOT, and don't really enjoy the idea of ending up flat on my back like a turtle!

Does anyone know of any reasonably priced chairs that have anti tippers? Or one that I could attach the tippers to? 

Thank you!