Of course in peak season the prices will be expensive. Salou is popular with visitors from all over Europe as well as being a favourite with the Spanish themselves. If you see a cheap price during this time of year I would be concered as to the standard of accommodation you will be receiving.
Anyway, here are a few sites for you to check out.
If you do book something then can I suggest you book using a credit rather than debit card. A lot of accommodation only companies have failed in the last few months and credit card will offer you much better protection against losing your money should the worst happen:-
I strongly recommend the Esmerala Apartments in Vilafortuny. Across the road from a great beach,British style entertainment every night and the cheapest beer in the area.Plenty of good cheap restaurants and a chippy close by and the Esmeralda has very cheap rates. They have an E mail address.