Just in case you missed something or I misunderstood what you were saying, specific steps below-
Click Mechlab tab
(edit to include this) Click on "Owned Mechs"
Click on empty mechbay
Click "Create New Mech" that appears on top of empty mechbay that you clicked
In the new window, you will see on the right below the word "Battlemechs" 5 icons marked * (Hero), L (Light), M (Medium), H (Heavy), A (Assault)
Click on the mech class you desire, then click on your preferred mech and variant.
Picture of the mech should appear in the center with certain details of the mech on its immediate right.
At the bottom of the details, you should see "Buy MC" "Buy CB" where the MC and CB prices are displayed. If you do not have enough MC or CB to purchase the mech, the words "Not enough MC / CB"" will appear in red above the prices.
If the CB price is not greyed out and the red letters indicating insufficient CB do not appear and you still cannot make the purchase, please email support@mwomercs.com with a screenshot and ask for assistance.
Hope this helps
Edited by p4r4g0n, 09 February 2013 - 11:23 AM.