Will using regexs in the primary key slow down searching?

[Ixiterra]

I am working on a postgresql database that will basically search for part numbers and put a lot of data together (what else). Most of these part numbers will be pretty standard, and will just be something like "4001". However, some manufacturers use lots of prefixes and suffixes, and I realized it would make sense to use something like "4001(A|B|C)" instead of making 3 additional part numbers. The database might eventually be something like 40-50 thousand parts, with maybe 25% or so of those containing regular expressions. Would that significantly slow down a search? If I don't use the regular expressions, it will increase the number of database entries significantly anyway, and make my life a lot tougher.

What do you think?