I must admit that I used to buy cheap tyres, but I did many stupid things when I was younger. I even have a video clip of picking my newborn son up from hospital and he went straight into the back of the car on Mrs Stony's lap. No car seat, no seat belts but thankfully non of them died.
It's hard when you're on a budget and you're still trying to stay legal, but the extra money for tyres is one of the things that you really shouldn't skimp on. Braking distances, handling, performance in the wet, and the risk of high speed blow outs. It really isn't worth the risk.