Since you're VIP, you should get Expensions that are not Free to VIPs. Will not recommend one specific because don't know what you're comfortable running solo, but here a list of the Adventure Packs and you can see which gives more Favor per pack and plan your spending.
It is a rough ride. I'm actually doing 2 ETR + 1 RT per life and couldn't reach 7,5k even doing Heroics quests without a Epic Variant and saving Epic/Legendaries for first time Favors. You will really need to dig up on less popular content, Raids and Challenges (both Cannith and Eveningstar).
I ran (mostly) non-epic quests in heroics (with the exception of IOD cause I wanted to try it out) and that got me to aroooound 4,500 favor by level 30-ish. Could probably add another 1,000 if / when I ETR. In no way optimized so I imagine one could get more if they tried, but not all the way to 7,500.
After you get some nice Legendary gear isn't that tough to solo EE/LE/R1. I was just giving the OP some insight how strenuous the way to 7,5k can be. Is a real challenge to those up to it.
This. A +8 tome is pretty cheap if you get the 10th Anniversary of Free to Play Launch Bundle. Pick it up with 30% "Determine Your Discount" campaign that ends today.
I still struggle depending on the build / how many lives my toons have, so YMMV. It's not always "can't complete" tough (though I'm yet to solo Slavers, for example), but certainly "takes a lot more time than with a group" tough, and if you get an unlucky death toward the end of a long quest, your only options are use a cake or retry from the start (if R1).
You are basically going to need to own all the content, and i dont suggest you do that unless you are ready to spend a boat load of money. Most people would say the state of the lag in the game currently would not be very encouraging to be forking out for all the content.
In a first life without the right resources yeah, I agree. But, with some preparations one or two deaths can be circumvented:
I mean, I don't wanna argue too much on this because everyone's experience is their own, I just don't want to oversell how 'easy' it is to solo some of these quests. It's still challenging, there are ways to make it less challenging but they are incremental and sometimes of limited use. Jib is only good if there's a shrine nearby and if you don't have a dozen mobs on top of you. Hire is good and I use that tactic religiously, but newer quests love their big fights in big open rooms locked with barriers, at which point it's anyone's guess whether the hire will survive the 5 seconds before they can case Resurrection. 3) is pretty much mandatory stuff but it still won't save you if you get unlucky - especially in quests like Slavers where you have a dozen archers pelleting you from all directions at any given time.
In the Flesh is honestly not as bad anymore (as long as you have a Deathblock item), unless you try to do the ghost beholder optional. It's now in the 'older quests' category, which have not kept up with the power creep. I can think of worse quests to permadeath at that level.
My recent count was around 3~3.5k, but I did not necessarily try to maximize favor (e.g. ran some slayers, repeated Shadow Crypt and LOTD etc.)
Not saying that by any means. Just pointing out to OP what can be done, yes is a challenging, but doable. At the current state of DDO lagfest, dying is almost a guarantee.
