I dont think cheap is the target but rather value for money.
I would rather buy a set of tyres that could be more durable and have a foam that can give me a fair bit of life possibly have durability to last a race day.
At present I use 2 sets of tyres per club meet.For us in South Africa it can get expensive as we have to deal with a strong Dollar exchange.
We pay about R180 - R200 for a set (4) of tyres which is about $30 - $35
and that is a good price.