That's unusual. To get a sense for the amount of variation in the results just due to random starting seeds, I'd run your HB four or five times (should be fast, given your small sample size), using seeds of 1, 2, 3, etc. (you can change the starting seed on the Estimation Settings link within the ACBC HB settings area. If you're seeing quite a bit of variation (in price importance) when only the seed is changing (everything else is held constant), then perhaps this is due to lack of convergence. Remedy would be to triple or quadruple the number of burn-in and used iterations.