Can't decide* upgrade or not
 

I have a few licenses* one of them (3.7.2) is expired but with active blog license.
I wanted to renew that license to upgrade to 3.8.4 but till i earned the money* the 4th version knocked the door :)
So* to make it short* can i upgrade to 4th forum version and have the same look/style like i have now with 3.7.2 with blog and use the mods i was using and mods of 3.8.4 version?
Also* how much will it cost me to upgrade if i already have VB and Blog on that domain? I don't need the CMS suite* just forum and blog