I don't have one but I'm going to buy (as soon as it gets a little colder) a new stable rug from Ruggles because all of the reviews are brilliant, I've never heard anyone say bad things about them. I've got a heavy horse so my options are limited but, of those limited options, Ruggles have the best prices and they've been really helpful with supporting me in finding the right size.
Where abouts are you? As A company called Red Horse Rugs near Stratford had some bargain stable rugs advertised on their Facebook page. I bought a 300grm standard neck for £20.
My first point of call for rugs is a company called TwoTimesTack, they often have bargain rugs - they have three or four medium stable rugs on their site under £35 at the moment with the cheapest being a tenner, their postage isnt too bad at just under £5
they have a fab shop in Oxfordshire for anyone nearby, so many times I have gone in there needing a specific rug in a specific size and they've always come up trumps - really helpful
I love my turnout rugs by Ruggles but recently bought a stable rug and it doesnt cover the sides even of my slender pony, it only comes about two thirds of the way down her sides, its a lovely well made rug and I am using it but I am really disappointed with the depth