Unfortunately, DIRECTV only offers the $10 monthly broadband bundle via Sonic.net to customers who have not been DIRECTV customers for at least a year.
So, your only way to save would be to switch to Dish for two years, then to DIRECTV. But by then, there is no knowing if we will still have this bundle available.
A better bet might be to phone DIRECTV and see if they will match these rates, or come close, as part of a new two year contract re-commitment.
Of course, you don't have to depart Sonic in any of these cases - but switching Pay TV providers to save money may be worth considering.