G'day Thursty,
Nice little Twin you have yourself there.
Great mowers. A few years ago you could pick them up from the kerbside for nothing, or at worst a carton or $50. Reel mowers, especially SB mowers are enjoying a resurgence in popularity. Some people are paying lots of money for them, others are asking insane money for them. There are a lot of "flippers" in the SB marketplace at the moment, but I think there will be a place for nicely tidied up, well priced units for a little bit longer.
I'm essentially running "no budget" for my 14" SB project, only because I intend to keep it going for another 51 years. They tidy up well and most parts are available easily. Just shop around, many people are jumping on the $$$ train and are selling "Scott Bonnar" bearings for $20+ each when you can pick the same thing up from a bearing supplier or mower shop for $3-10, for example.