Try Equestrian Clearence. Don't go for the named brands. if you look in the clearance tab you usually find a "pot luck" type option where you can specify the size and weight, style etc but what make turns up is a mystery. They are excellent value and often really excellent makes as well.
i bought a REALLY cheap t/o on t'interweb somewhere, with the intention of it being raff's 'spare' rug... but it ended up being his best one, as i loved it!
i think it was axoim, or axiom make. they do a tough dernier for rug rippers too xx
does he rip them off? he could be overheating if that is case sometimes (happened to me when I had to go up a rug tog as the wrong one was sent back from the cleaners) Result next day - nearly new rug ripped completely in two.
If he is a horse that is just destructive - I was told to put washing up liquid on to stop mine - BUT!! no idea if its poisonous and of course, appreciate it needs regular top up!
Well don't whatever you do buy one from horserugs4u.com, they took my money, (they say on their website that you account is only debited when rugs in stock) 30 days later, no rug, no refund (as requested) no reply to recent emails or telephone calls. Fortunately I purchased the rug on my credit card so I will hopefully be re-imbursed..