The polystyrene capacitors may be worth keeping, though at least the smaller ones are usually not that expensive. The start to become hard to get though.
Most of the properties (especially the leakage current) are good, but they are sensitive to chemicals (even alcohol may damage them) and heat.
In many application one can now use C0G MLCCs instead. There main use now is for very low leakage, e.g. in electrometers, pA meters.
Audio transformers can be usefull to avoid hum from ground loops, e.g. when combining many parts that are grounded.