Question about 2017 Volt LT - South Carolina

I’ve been reading the forums here and seen some deals for less than $300/mo. I’m wondering how that worked. I looked at a 2017 LT today and was quoted $356/mo for 36mo/10K a year lease. The sticker price was $34775 and the net cap was just over $29K. The only discounts I saw were $4600 from GM and dealer discount of $1200 or so.

Question - is this the best one can do right now or is the dealer holding back some rebates? How does the federal $7500 tax credit factor into this?