I know there are plenty of fakes and cheap high capacity cards on eBay which are really lower capacities then advertised. Surely there's has to be some reasonably priced cards out there which are just as reliable as some of those in the SanDisk or Samsung range.
What brand card have you discovered that is just as good and where did you get it? Would be informative to know what device your using the card in and how long you've had it?
Branded memory cards are already pretty cheap these days and I can't imagine unbranded to be any significantly cheaper. SanDisk memory cards come with 25 years or lifetime warranty which gives you a peace of mind when they are that confident in the quality. Better stick with the big brands if you care about the data.