Is a Yamaha Seca 2 a good starter bike? If so, what should I pay for a 1993?

[Mark]

The owner wants $1200 but it needs rear brakes, turn signals, and probably a tuneup. Is that a good price?

[Mr. Dave]

What "Jon" said. A thousand bucks cash, and you'll have the bike, almost guaranteed. If you can do some of the work yourself, you can save some cash on getting it going. Considering what it needs, the guy should be happy to get $1000 for a 17 year old bike that needs work. See what he says.
If I may offer some unsolicited advice, if you have not already done so, sign up for a MSC/MSF course in your area. You'll learn to ride properly in a safe environment, from trained instructors. It'll greatly improve your odds of surviving on the street.
Good luck.

[easygoing157]

would suggest the 600 may have too much go for a learner...(not sure if your limited to capacity or power where you live)

but the price is reasonable.. rear brake pads/ turn signals & a service/tune up would be less than $500.. so your getting a reasonable bike for under $2000