My scales are just tescos own brand - they were about £16 I think, digital, measure in Kg, lbs or st and lbs. They don't do that fancy BMI thing because quite frankly, BMI is only a rough guesstimate - only accurate way to really get that is to be measured with the little nippy calipers apparently!
Mine are glass and very easy to keep clean. You just tap them to switch them on.