I don't have the experience of a lot of guys on here but from a relative beginners point of view I would agree you don't need to spend a lot.
Hand planes have allowed me to make some bigger items than I would have originally imagined. I actually had a planer thicknesser when I started making my sons bed, but I had not finished rebuilding it so I had to make the whole bed from a scrap Conservatory roof using just my bandsaw, workbench and planes consisting of a Record No. 5 1/2, my fathers old Stanley No. 4 and a newer Stanley block plane that I was given.
I have since been given some planes and bought some from e-bay. All are Record, 1960's or older, three date from before 1940 and all work fine as they are. I have not changed any of the blades, but have stripped and repainted a few that were a bit shabby. I have also succumbed to a bit of fettling on the base of the planes but to be honest all of this after I made the bed. Changes that have improved the appearance have made no difference to the performance of the planes. Although I have all of these planes, I am not convinced that I need any more than a smoother and a Jack. It's hard not to start collecting them though! The only planes I still need are a rabbeting plane and a shoulder plane. These will also be picked up secondhand and I will probably stick with older Record models. At some point I may get around to tiding up the chrome on the Lever Caps of the N0. 4 1/2 and get the Nickel re-plated on the 5 and 6. Then again, I am just getting the pleasure of using them as they are.
I made the bed using my No 5 1/2 shown second from the right here:
and shown again here, the 5 1/2 I bought for £29 including postage and has had nothing other than the blade sharpened
I have not paid any more than £30 for any of these including the 1930's No. 6 and No. 5
Best one was a free No 4 which looked like this when my Neighbour gave me it (he was originally taking it to the tip):
Dunked it in a bucket of rust eater, after some painting and a clean up looks like this:
The bed I made is nothing special or clever and is made from some pretty low quality hardwood, but the wood was free, my son needed a bed and I learned a lot about planing by hand as I had no other way to do it. Still learning!
And
Good luck
Nigel