Value is always tricky. It was worth exactly what you payed for it-the amount the buyer and seller agreed upon in fair trade. One in good condition would be worth more but there are too many variables for a decent appraisal. I have 2 model 27s, very similar to your machine. One was a gift from a member here and I payed $25 for the second one in a beat up treadle. They use standard needles, long bobbins are still available new too. I love sewing on mine. They will sew anything that fits under the foot.
It may not need anything more than a good cleaning and oiling to work. Your manual will have oiling instructions. It takes a lot to kill these things. If you haven't messed with old black machines be sure to read the sticky and watch the videos on cleaning it. Some cleaners will destroy your decals and finish.
You can download a free manual from Singerco.com under resources.
Rodney