In my view if you have a grand to spend and don't know what to buy, DON"T BUY ANYTHING. save your money 'til you know what you need!
The problem for a lot of us home recorder newbs is we tend to take the following path, and I'll use pre's as an example
*Start out plugging into on board sounds. Sounds awful buy an interface $200
There is an immediate improvement
*After a while start reading posts online become overwhelmed with gear lust and feel a desperate need for "better" Preamp, don't have much money so buy a DMP from m-audio $200
*After initial Euphoria of being an "Outboard" pre owner realize can't really hear any difference
*More online reading leads to realization one "must have" an FMR Audio RNP $500
*feels like recordings are sounding better but begin to second guess pre as the cause as time, effort and experience have given better recording technique
*Read gearslutz and realize one "Must have" a color pre to give analog oomph spend $650
*mixed feelings about color pre purchase, can't always tell the difference and only need color on some things anyway
*Hold off on more purchases concentrate on getting better technique, gear lust is under control.
*Buy a really good quaility "higher end" pre, hear real improvement in clarity, transients and depth of recording spend $1500
The point is to get to where you ultimately wanted to be you only really needed the Audio interface and "high end" pre costing in this example $1700
To get there, however, we spent a grand total of $3050 messing around buying bang for buck "Upgrades" that actually barely move the needle at all and so needlessly spent an additional $1350 to get no real improvement.
This is of course what the low end manufacturers want us to do as it keeps us spending money on products we don't ultimately need
I think the same is true of plugins.
Learn the ones you have inside and out until you can put your finger on exactly what you need and why you need and get a product that completely fulfills that need
Spending a grand based on what a bunch of random strangers on the internet think may not give you that "Pro Sound" we all ultimately want
Hopefully we all learned our lesson early on and bought based on what we really need but even if that is the case plugins that meet our specific needs and goals may be completely inappropriate for you
The best bang for buck whether you are ITB or OTB is in buying only what you need and not what you don't. Not chasing the elusive magic bullet, spending thousands on "Bang for buck" plugs or gear that ultimately don't give us what we need to get the sound we want.
As a random internet stranger myself my opinion may, of course, be complete bunk too
YMMV
