Photo etched (PE) parts are a great detailing accessories but not necessary cheap. Use them wisely. I apply them to where viewers are most likely to see them. For example: Brake calipers mounts, engine mounts, licence plates, triple clamp and handle bars, to name a few. If you look closely at older Tamiya kit like the Katana you can see that the bolts are simulated with simple round extrusion. Super glue a PE bolt head there and you can see the result immediately!
There are many PE accessories in the market. From specialiesed parts for a specicific models to general detailing hardwares. The ones I use are mainly from F1 Specialties and Scale Motorsport. F1 Specialties are the best; they are thicker and come in assorted size. As for Scale Motorsport's, its the most economical and easy to use, as it is already rubber backed for easy removal.
This is an example why I say it might be a waste money: Hose Clamps are easily simulated with strips of foil. But the above hose clamps is very detailed! Right down to the grooves!
Detailing PE set for specific bikes are now readily available. Expensive but good. Currently the range is very limited and seems to cater for the few popular GP bikes only. NSR, RGV and YZRs
Other PE detailing accessories range from washers, fasteners' heads bolts, nuts to hose clamps! There are many manufacturer and most are for use on cars but they are easily adapted for bikes