[rules-users] returning random limited query results

I'm trying to implement some suggestion functionality. Is there an efficient way to query for X random facts matching some constraint (e.g. ten random cheeses that cost less than 3 dollars)? I'd rather not generate the complete list if there's a more clever way. Unfortunately, the constraints are customer specific; otherwise, I'd just create sort of a central buffer list and dole out the random goodness to all takers. thanks, -Jess