Quite seriously steve, tell him to get at least ten of those bottles on ebay, i guarantee having watched several auctions in utter amazement he can't possibly get less than a tenner a bottle so theres an easy £100 for him there which would buy him a very very nice model or two.
Personally i'd struggle to use up 2 bottles in ten years but then I use it selectively, not on everything and i'm not a quick builder.
Johnson Klear wax 500ml unopened | eBay
Currently 6.59 over a day to go
Johnsons Klear Original Floor Polish, unopened, new | eBay
Currently 6.00, over 3 days left.
JOHNSONS KLEAR 500ML UN-OPENED, BRAND NEW | eBay
Sold listing, £23, yes really and this is an old and cloudy one.
Johnson KLEAR | eBay
Sold listing, £21
Johnsons Klear Original Floor Polish, unopened, new | eBay
Sold listing, another, £21
JOHNSONS KLEAR 500ML UN-OPENED, BRAND NEW | eBay
Sold listing, yet another, £23
I could go on but you get the idea. Show him these links or mug him, LOL
I'm going to add to this, £20+ for 500ml of gloss acryl varnish, what idiot thinks its worth this?
The hannants xtracryl comes in 100ml pots for £3.25 and thinned (water) will at least double that if not triple.
Y'know i'm half tempted to sell my 3/4 full bottle.