It was a TV series in the 60s, long before the film which admitdely is a bit "middle class" but still good fun. I can't remeber how old I was when I finished the books, probably about the same as you, but the local librray only had a few so I had to order them in advance, wait for them and then order the next. Many were brand new so they probably had to buy them specially. A few years after we got married I saw one in a local book shop, they had all just been re-published in paperback. I bought the lot (around £50) and then had to explain it to SWMBO. She didn't bat an eyelid and said that it was probably a limited run so I was right to get them while I could. I got them out to re-read last winter and already the paper is deteriorating so I am not sure that they will be there, as planned,for when I retire and want something to do on cold winter afternoons. In the mean time I have been buying the earlier edition hardbacks on e-bay for a few quid each. they are notmally tatty but they smell and feel right plus the paper is going to last much longer.