This is the quote from the Scalefinishes website. "Scalefinishes colors are solvent based Acrylic Basecoats and require a clearcoat to achieve a gloss finish". If they're enamels, spraying lacquer clear over them won't yield good results. I've heard that TS13 is a little hot in relation to other hobby lacquer sprays.
You can get it through eBay for 8.57 http://www.ebay.com/itm/like/331836934396?lpid=82&chn=ps&ul_noapp=true Walmart supposedly carries it too. It ain't cheap, but if it works well, it might be worth it.
You can get some idea of how much paint you have left by weighing the cans. The Tamiya and Model Master 3 oz. cans weigh 137 grams full and 62 grams when empty. The weight of paint and propellant is 75 grams which calculates to 25 grams/oz. The Tamiya primer cans are 5.4 oz. and weigh 210 grams full and 80 grams empty which calculates to 24 grams/oz. Not enough difference between the two so I just divide by 25 when checking how much is still in a can.