I did go back and dig out my costs from a few years ago, prices have gone up since then so I did some price checking (over 30% in 5 years).
For 2k base/clear and whole car in primer without any major repairs or corrosion to deal with its £325-454 not including abrasives or oven time. The cost difference is depending on paint brand, primer brand and paint colour.
That price is for a 7.5l hs clear kit which is LOADS more than you need and also 5l thinners, 5l hardener which again is loads more than you need. I usually use left over thinners as gun wash anyway.
Tack rags are £5 for 5, panel wipe is 30 for 5l. - just from regular supplier, much less in bulk.
And I would estimate £100 on abrasives. Abrasives, tack wipes and panel wipe I tend to always have a few tins/packs so the cost is spread across multiple jobs but agree some abrasives aren't cheap!
This is using Jawel paints and the price is INCLUDING VAT. This is 3l base, 3l hb primer and hs clear.
So I more or less stand by my £500 estimate for an average sized car done in 2k base/clear for a non professional. For a professional outfit who mix paint on site and buy primer/clear/abrasives and cleaning materials in bulk/trade their materials cost price is naturally lower.
You can do it for less if you use common paint colours or non-brands or a small car obviously.
EDIT* Those are current prices