So you are looking to replace the entire groupset. The Shimano Altus M2000 groupset is probably a cost effective upgrade or your old system. It sits above Tourney. Things have moved on a bit since your 810 was made. Even the entry level Altus is now 9 speed. It isn't going to be cheap...not that it's expensive in the grand scheme of groupsets...but getting it all at once...and buying a new rear wheel. If you look up the Shimano web site there a whole world of info on groupsets from 7 speed all the way to 12 speed.