I spent about £2,000 on a Bianchi in 1999. I'm not sure what that would be equivalent to now. That had a 9-speed Campagnolo groupset, but it wasn't Record or even Chorus, it was the then third-in-range (old model) Athena. The wheels were pretty good - Campagnolo Protons. Though it was a very good bike, I could have paid more and got a better one but the law of diminishing returns would have kicked in with a vengeance.
I spent about £2,000 on a CAAD5 Cannondale a few years later. It has 10-speed Chorus and I transferred the Protons over from the older bike. TBH, that bike is about as good as I need, though I occasionally lust after something better.
Most of my riding time is spent on a steel-framed Basso which is a few pounds heavier than a bike needs to be but I enjoy riding it. I do prefer the aggressive ride quality of the Cannondale when I'm fit enough to take advantage of it but I currently need all of the Basso's lower gears. It seems a bit silly to worry about 5 pounds of bike weight when I am 45 pounds overweight!
If I had £3,000 to spend on bikes, I would consider changing the gearing on the Cannondale, and spend the rest on a really good titanium audax/light touring bike. I'd keep the Cannondale for when I wanted to ride fast and the Ti bike would be fine for everything else.
I'd like to try a carbon fibre bike but I couldn't justify buying one while I still have the Cannondale and there is no good reason to sell that, especially since I'd be lucky to get even £500 for it.
I like my 853 Rock Lobster hardtail MTB, but it is a bit heavy so I could maybe see myself getting a lighter MTB in the future once my own weight isn't such a big part of the total. I reckon I could get a bike about half a stone lighter than the current one. Mind you, this one is practically bomb-proof and that is important for a MTB that does actually see some proper heavy duty bridleway action.
I might spend more than £3,000 on a very specialist bike like the semi-recumbent tandem that Uncle Phil & Mrs. Uncle Phil bought recently, but no matter how wealthy I was, I'd consider it a bit OTT to spend that on a standard racing bike.