I have the DAL 55-300 and something like 95% of the shots I have taken with it are at 300mm. So this makes me think a ~300mm prime, preferably fast-ish (or at least not super slow) would make a nice addition to the collection and improve the IQ of my long shots. AF would be nice but not a necessity, but at least being an A lens is required. What would you guys suggest? The DA* 300mm F/4 looks very nice but it's a bit pricey for the amount of use this lens would get from me. Is there a cheaper/older/off-brand option that might work well enough to improve IQ over the DAL 55-300 at 300? Thanks!