September, the Spey season is close to finishing, there are a lot of fish in the river but most of them are coloured (close to spawning). They have seen every Cascade and Ali Shrimp possible, so a change in tactics often pays dividends.
Prices can be cheap, for the Spey. Look at fishspey.co.uk
Also consider the Ness at Inverness the town water can be excellent but it is a hard fished water and unless you can throw a long line your chances are much reduced. Most of the locals are throwing 25+yds.
If you would like a guide for your trip, PM me my prices are very reasonable.