Got the BBQ Cover about 2 years ago and it has stood up well (other than the dog chewing off the velcro straps recently).
I acquired the same BBQ rotisserie earlier this year - after missing out on the last sale, as it sold out fast - and use it regularly. Family love the meat we cook on it.
6 Burner Premium BBQ Cover ea $ 29.99 *
Heavy duty PVC
Weatherproof
Velcro ties for secure fit
210(W) x 60(D) x 105cm(H)
Link to cover: http://aldi.com.au/au/html/offers/2827_23560.htm
BBQ Rotisserie ea $ 29.99 *
Stainless steel 240V motor
16kg weight rating
Heavy duty spit prongs
Suitable for most 3,4 & 6 burner BBQs
Link to Rotisserie: http://aldi.com.au/au/html/offers/2827_23561.htm
It's a good weight rating. You migh find cheaper one's (like i did at big W) but the insides are made in plastic, and plastic and heat dont mix well, and you might have to (like I did) buy a more resistant one.
I also make a "heat deflector" out of alufoil to put in between then roaster and the BBQ.