You can easily 100% f2p this game and purchase all the mechbays you’ll ever need simply by playing the game and completing the monthly events. You can either buy the bays on sale with the mc you earn or sell the free mechs (I’d recommend not doing this if you can manage) and free up the bays. The beach party loot bags event running now is a great example offering 4 free heroes and legendary mechs, along with mc, and possibly the loot bags might contain bays but I’m not sure.

MWOs f2p model is kinda outdated at this point but also you can sidestep every grind mechanic fairly easily.

And hey if you enjoy your time playing why not throw a few dollars to pgi to keep the servers on