Just my opinion. I've never seen blockbuster sales at some time of the year for Studio One. While I fully understand budget concerns and have my own as well, I think it's best to get what you need now.
With that, version 5 is excellent and has all of the essentials, so if that's good for you, you could wait for that meh, sale.
Only here's why you shouldnt. With version 7, Presonus has opened the flood gates on Studio One accessories. From the 3 new sample players, plus the Orchestral sample pack (around $80), the Presence Editor (about $80), the conversion pack, etc, etc. Add to that, the new bersion 7 clip launcher, auto stem export, auto-tempo, and as you can see, waiting for some $20-$30 savings is like waiting for a midnight bus, to get you to the show late, to save a few dollars.
Others might have a different perpective, but this new version 7 is undoubtedly the biggest leap in accessories and freebies. Granted, you may not care for them. I'd honestly buy right now.