Wow, the idea of using pond dechlorinators had never occurred to me.

*runs off to buy pond dechlorinator*
For people who like to know what's in their dechlorinators/water conditioners, and/or DIY fanatics, the German company Drak-Aquaristic lists the ingredients (and their concentrations) in their dechlorinator:
14.81 g/l potassium; 12.39 g/l DTPA; 9.21 g/l EDTA; 9.0 g/l carboxymethylcellulose (CMC); 8.76 g/l HEEDTA; 6.02 g/l NTA; 5.0 g/l Na-humate; 2.52 g/l calcium; 1.53 g/l magnesium; 1.13 g/l thiosulphate; 1.0 g/l methyl paraben; 0.5 g/l dexpanthenol; 0.2 g/l Aloe vera (Dried Extract - 1:200); 200 mg/l iodide; 10 mg/l lithium; vitamins (500 mg/l C; 100 mg/l each of B1, B6, niacin; 50 mg/l B2; 5 mg/l B12)
That stuff is meant to be dosed 1 ml/gallon, so I guess an industrious person could make their own dechlorinator using the same guidelines. You probably won't save much money compared to using pond dechlorinator, though. At the very least, if you run out of dechlorinator, you'll know you can use your own Vitamin-C supplements to dechlorinate your water.
The active dechlorinator is Vitamin-C. It supposedly inactivates chlorine at a 2.5 : 1 ratio (2.5 ppm of vitamin C will neutralize 1 ppm of chlorine). Most commercial products use sodium thiosulphate instead, because liquid vitamin-C needs to be stored in the fridge and can't be stored for very long. The advantage of vitamin-C is that any excess of it is guaranteed to be harmless and/or nutritious to the fish.
DTPA, EDTA, HEEDTA and NTA are all metal chelators for the purpose of removing free copper and other heavy metals from tap water. You can omit them if your tap water has no such issues.
Dunno what Na-humate is supposed to do there, but I assume it's intended as an organic chelator. It's a humic acid. Peat/carbon/bogwood in the tank would probably do whatever this is supposed to do.
I believe the CMC and Aloe Vera are supposed to protect the mucous membranes of the fish. I'm sceptical about that, and probably wouldn't bother.
Everything else is just for trace nutrition and fish skin/mucous layer protection. I'd leave it all out.
edit: Overlooked methyl paraben there. It's a mild anti-bacterial agent intended for the preservation of the stock solution, according to their home page.