Since you have been tying for a while , I will assume you have a good vice with lots of holding power for the larger gauge hooks . Speaking of hooks , the style hook is very important . I prefer a good quality Bartleet hook ..... Partridge CS10/1 or Daiichi 2051 for most spey flies , I leave the heavier Irons (CS10/2) for standard steelhead and salmon wet flies .
For body materials , you can get by with wool .... natural type (100% wool) four stranded type will give a "buggy" or "vintage" look . The synthetic (lycra) will give a sleek , shiny appearance , almost floss like . You can use the same dubbing blends that you use on other flies , just pick your colours . I like metal tinsels and wire , I stay away from mylar ...... just doesn't withstand the salmon and steelhead . Matter of fact , it would rarely make it out of the vise . I do tie with great pressure on my tinsel ribs and wire counter ribs and the mylar would never even hold up during the tying process .
Pheasant pelts are a very good source of body hackles and collar hackles . Plus the breast and flank feathers can be used as winging material ..... I love pheasant You can always purchase teal and guinea hen as well , both are used on a multitude of patterns and very inexpensive . Blue Eared Pheasant is well sought after by most spey tiers , however on a limited budget , it would take away from purchasing a lot of other needed materials . a BEP pelt would run you at least $150US and a package of a dozen feathers is around $10US . I would rather get a few Ringneck pheasant pelts in natural and dyed colours and a Golden pheasant pelt with the head and crest and some good quality schallapan in an aray of colours before committing to a hefty purchase like the BEP pelt .
Goose and Swan shoulders come in a variety of colours and are fairly inexpensive for winging material . Good quality Bronze mallard can make all the difference when tying old school shrimp patterns , like the King series , Speals and Riachs (Reech) . Fortunately , good quality bronze mallard is not that expensive
Hope that helped some what .....