The key information that you haven't provided is where in Turkey are you leaving from? and what is your mode of Transportation?
I just got back from a month long tour of the Middle East and was in Aleppo almost a month ago. I had gotten my Syrian visa ahead of time. The visa now costs $131 to match what the US is charging other countries. We flew from Istanbul down to Gaziantep and then crossed the border. From GZT, it will still take you at least 2 hours if not more to get to Halab.
Overall, unless you are flying directly into Aleppo, I'm not sure that you can do a day trip. If you choose to cross from Adana in Turkey, I believe it is close to 4 hours to get to Aleppo.
I would strongly suggest you spend a night if going there to fully explore the souk and especially the Citadel.
Sorry but I have no information about the tour company having the visa fee waived. I would not recommend trying to get the visa at the border - you will get it but this will probably take 6-8 hours of waiting (check out the thorn tree on lonely planet for other folks experience).