Categories of Users

[Edward]

I have over 500 products in about 25 categories
I have 12 different Markets (user groups)
I have 2 price groups for all products, wholesale and retail.

I want to completely password protect the store.
When each of the 12 different markets (user groups) logs in I want to allow them to see only the subgroup of categories that pertain to them. Each category should be accessible by more than one group because some categories are sold into more than one market.

I am assuming that ShopSite can handle the 2 price groups by use of the coupon features.

I am assuming that ShopSite cannot handle the segmentation of product categories based on user and that I will have to program a front-end to control this. I have not done exactly this before and am looking for direction from others who may have handled a similar problem and what the complexity of a solution might be.

Thanks .... Ed