How much might this cost?

Pretty broad question, and the anser is "it depends" because there's a lot of variables.

Heat dress - are there inlays? Fretboard bindings? Anything that needs to be protected raises the price. And on top of that, many repair shops don't have that capability... they'll be sending it out. If you really need a heat press, it's best to deal with a luthier. All luthiers will have heat press equipment for bending sides, but not all will have the tooling for straightening necks - they do that with a plane. On the other hand, few repair shops will have any heat/steam equipment, but they'll be happy to charge you for it (and some will just adjust the truss rod and tell you they straightened the ned!)

Level & dress - the more frets, the more $. And fretboard binding can add a little bit. But this one is fairly simple - figure about $2.50 per fret (for most guitars, about $50 if it's a stand-alone job; but many shops will combine this with other set-up tasks like adjusting intonation and action - so it might cost more)

Clean electronics - again, it depends. How many pickups? Standard pots or push/pull? Just a cleaning, or are you going to need some soldering work?

For the whole job you're asking about, I can see pricing from roughly $100-300+.

Like I said, it depends :)

Hey Noteboat, thanks for the reply. I didn't realize how broad that questions was. Thanks for the info. Here's the guitar that I'm looking at...

http://elderly.com/vintage/names/silvertone-model-1448-%281960%27s%29--30U-14964.htm

The old Danelectros / Silvertones didn't have an adjustable truss rod. That's why the neck needs a steam press to straighten it out. This is going to be a constant problem.

Another thing to consider too is that it may need to have some frets replaced as well. If you have some heavily worn frets and try to level all of them down to the worn level you will go too low. It would be better to replace the few most worn frets and then level. The low 3 in that picture look worn. That's maybe $10/fret.

Are you looking to buy this as a collector or as a player? If as a player you might want to consider buying an updated Danelectro. There's a guitar shop / luthier in Berkeley, CA whose owner is a real Danelectro nut. He bought up a warehouse of the Danelectro remains in the 70's and has been building stuff from them. He's updated them with real truss rods and such. He's a bit of a character as you might expect from being a Danelectro nut but he's got some interesting stuff and some interesting stories (he is apparently the guy who sold the Danelectro guitar to Jimmy Page and also supplies other big names too).

Fat Dog's World Famous Subway Guitars