Do not put an industrial dehumidifier in a bedroom for a bit of damp. It will draw the water content out of any wooden furniture you have in there. If you leave it running after you have cured the damp it can even start to dry out your lavatory/bathroom.
Just do an internet search and find something you like at a price you are happy with and then search for reviews on the product. About 5 years ago I bought a B&Q one for about £70/£75 and once it had done its job I sold it again on Gumtree for about half what I paid for it within a couple of hours of it being advertised. So it cost me next to nothing and it was very good.