First, on the 8.8AH battery - I have a 16AH, same voltage similar motor, I pedal some but not a lot, mainly on takeoff, and 30 miles was close to a max range brand new. They fade over time, you want one of the 80%-90%-100% selectable chargers to prolong life. A 12AH would be a better choice, so choose one.

Next, for flat ground, the extra expense, maintenance requirements, and installation difficulty of a mid drive is very much hard to justify. Better profit margin, though. You can choose a very much more cost-effective solution.

Bicycles come in many varieties, e-bikes less so. So choose a bike which is comfortable for you.

I choose a lightly used, Specialized Crossroads, $200.00. A steel fork made a small, lightweight geared hub, chosen for lack of cogging drag, a simple wheel change. Front kit leaves drivetrain unchanged, easier install and makes possible an IGH for necessary higher ratio in future. I used an MXUS XF07 motor because many user reports have it passing 10,000 miles, as mine has just done. Could not find any significant problem reports on this motor. 18mph cruise in 700C wheels. No hills to climb make this feasible. Kit I choose also had a fully-potted controller for water proofing, necessary for me in Florida. $325.00

Finally, I choose a 36V, 16AH EZee brand battery, mounts horizontally on a rear double-decker rack in a sealed plastic case, with keyswitch and lock to the rack. The 16AH broke your budget by a small amount. but a 12ah battery will fulfill your needs and keep under budget. I think it is $695.00. Battery is most important and expensive single component, do not go cheap here.

All quality components, all chosen for a specific task, similar to yours but more range and frequent use. 3 years and 10,000 miles later, I have replaced several brake pads, got a more comfortable seat, oiled the chain regularly with a wax compound, bought one new tire, fixed a few flats, and had ZERO problems or issues with the motor or battery.

Edit : All items shipped from North America from reputable dealers with sterling credentials and replacement parts on hand. Motor price included shipping, rim, tire, also custom connector to match my battery. Andersons.