Is there a rule of thumb for pricing commercial building rent?

[Amy Raye Rogers]

This weekend we came across a commercial building that looks like it could be a great opportunity.  It's currently owned by an architectural firm, who owns it outright.  It's 3,000+ square feet and listed for 339k.  It has a really cool design and very functional layout. Does anyone have a metric for determining what the market rent on this building could be?  Is it based on the tenant, sq footage, comps??  Additionally what leasing structure makes the most sense?  If purchased, we'd probably market to professional services firms.

This is new territory for us, as we have only purchased SFRs to date.