Welcome shaun/sean ( you will have to let us know how to spell it )
you have many questions so I will try to get them best I can.
1) which wheel?
for $300 (US?) and that works with your ps4 and that has a shifter ( h pattern) I believe is a G29 by logitech , the shifter is an add on for $49 or so.
http://gaming.logitech.com/en-gb/product/g29-driving-force
most of us here play iRacing as it has the multiplayer aspect that cannot be beaten right now.
Some people play Assetto Corsa as well.
If the H Pattern shifter is not a dealbreaker then you also have the option of a Thrustmaster T300 doesnt come with an H Pattern shifter ( but you can get an aftermarket one as you can with any wheel )
http://www.thrustmaster.com/en_US/products/t300rs
Both of the wheels above come with paddle shifters on the wheel, which if you are playing iracing can be used in any car.
Both come with a pedal set which is fine to get going with but again, aftermarket pedals later on are always worth the upgrade.
you are kinda stuck with the wheel rim you get on the G29 , the t300 rs wheel rims can be swapped and there is quite a large range.
As far as diminishing returns on wheel sets? I don't think there are any, with racing hardware you get what you pay for. As you move up price wise though , the next step is Fanatec equipment
https://www.fanatec.com/us-en/wheel-bases/csl-elite-wheel-base-usa.html which a lot of us use although I am unsure if they have PS4 compatibility. After this comes direct drive wheel sets which start at 4 figures and although very very good are a bit overkill to start off with.
if its $300 canadian?
Your last point about VR, iRacing, DiRT Rally, Assetto Corsa and Project Cars all have VR support in one form or another, to get the best experience from it though your PC needs to be THE SHIT as it is very hardware intensive.
HTC vive
https://www.vive.com/ca/ and Occulus Rift
https://www.oculus.com/ are the only two worth talking about, Occulus supports all of the games as far as I know and the Vive Supports them all but needs the (free) occulus software to run dirt rally and Assetto Corsa. The big two VR sets are around the same price and perfom just the same.
Both have built in microphones and some sort of headphones ( occulus has headphones attached VIve has a headphone socket) HTC has lenses that can be shifted forward so maybe more suitable if you wear glasses.
its pricey though so don't take my word for it, try it for yourself at a local best buy or a friends house, no description can do it justice nor any video, you need to see it for yourself. If anyone has any advice about one ask them first if they own one otherwise its just hearsay.
I think VR is totally worth it, others hate it or get motion sickness or it simply doesn't suit them because you are quite cut off the outside environment.
hope this helps, pretty much anyone here can help you get started with iRacing and one of us is probably playing at any given time of day, the other titles pretty much explain themselves.
See you on track!