Reasonably priced Dynamo

[snorri]

I could recommend the Miller dynamo, mine is still fully functional after over 50 years.
https://www.ebay.co.uk/p/Vintage-Bicycle-Miller-Dynamo-Raleigh-Phillips-Dawes-Schwinn-BSA/1023118162

 

[toffee]

Rose (or German stores in general) is usually the best place to look for dynamos. Something like this - https://www.rosebikes.co.uk/article/shimano-deore-lx-dh-t675-disc-hub-dynamo/aid:591997

Unfortunately all the Shimano ones are centre-lock so you would need an adaptor.

Spa Cyles have a SP PD-8 for £70 + postage which is 6 bolt - https://www.spacycles.co.uk/m2b0s133p3037/SP-DYNAMO-PD-8-Disc

Thanks everyone for your comments. Have ordered the Shimano one with a centre lock adapter.