Simple small business decision making scenario, need opinion.

Hi, I am new to posting stuffs in forums and English is not my native language. So please bear through the raw formats and unusual business terms.
So this is about decision makings, whether to buy or not. A product, 125 watt electric water pump, is currently undergoing a temporary promotion for buying in a buck.

Here are the details;
Cost per unit is $25
Gross profit per unit $2.3
Average monthly sales this year 150 units
Monthly sales is expected to rise 50%-100%, as per last years' statistics, in 3rd and 4th quarter of the year due to drought season.
Terms of payment 30 days

Currently undergoing promotion from our supplier is:
1500 units purchase within a week, for the next 3 weeks, will get a $0.8 cash discount per unit. ($1,200 total)

So, what I need help on deciding is whether to buy up 1500 units or not.
Not only for the 33% extra in gross profit, the chance that our competitors (yes, the competition is tight, hence the low margin) might be taking up the promotion would force us to follow their price, which means lower profit than what we used to make.
Any opinion is welcome. Please do not hesitate to ask for more necessary information. Thank you