I know different strokes for different folks but if your pro shop guy doesn't think a string loop is worth supplying you might want to find another pro shop. To not supply something as simple as a string loop is unheard of.

Ask him if they are that bad then why are 90+% of the pros and hunters alike using them? They do nothing but enhance a clean release, enhance accuracy, do not pinch nocks, keep the arrow nocked if you have to ease down, are lighter than brass nocks. Yeah, I can see why he wouldn't like them.[&:]

In adition to the above link you can usually find cut lengths in most all sporting goods stores that sell archery related gear.