I paid for heroics because my original plan was to just grind the whole way, but the grind really slows in the 50s and in the 60s even more, and in the 70s and 80s it is massive. So I gave up and bought 2 heroics. I then used those to power level the rest of my group up to 85 ish, and then joined them all together and continued on to 100+. I think overall it was worth it and saved me some time. But the grind from 85-100+ is still a long ride too, so you need to be prepared to do that even if you pay. I did a lot of Gribbles which was decent exp, but it still took a really long time and was super repetitive and boring. The only thing that kept me sane is that I enjoyed the constant tweaking of my Kiss inis. Also the gear you get with heroics is garbage so you need to spend the time to replace it all or you can't even do gribbles. I hit a brick wall around level 90 ish where I could barely kill anything in there. So I spent a bunch of time and plat to buy a full set of gear (RoF or something) and it made a huge difference. I mainly just needed it on my tank. With that, I could grind gribbles and my other characters got any gear that dropped along the way and I started making good progress.
I think buying three 110s for $350 seems like a decent deal (assuming they are all on different accounts). It depends what you want to do though. For me, I had never seen the game from about level 80 onwards, so I was happy to explore some of it. I did a lot of gribbles but I also did some full progressions. If you are only interested in getting to top level and then grouping with friends or raiding, then I would just buy the characters and be done with it. Also a level 110 can power level future characters SO FAST.
p.s. I actually quit EQ Live though once I reached 110. I am an idiot, I bought the expansion on 6 characters... and then a month or so later I was bored by it. It was ok but I have more fun on emulator servers because I can play entire raids by myself which I prefer, and it costs me $0. So I regret buying all those expansions now, but it was an interesting experience seeing modern EQ.