There are many good points made here, particularly that your budget is a bit light for a high-miler/quality commuter ebike, but to add one key point in my mind:
'Cheap Chinese Parts' is used far too liberally around discussion like this, and it must be mentioned that pretty much any 'brand-name' e-bike (including Rad) is using brand-name components - just higher or lower on the quality scale. Shimano makes derailleurs/shifters in a range of quality from the entry-level Altus and Acera, up to the Race-ready XTR. Sram does the same thing. Brakes and other components from Tektro, etc, fall on a similar scale. You can buy bikes by any manufacturer with that whole range of parts installed.
It is certainly often true that you get what you pay for, and if a brand is using no-name components, well buyer-beware. But if a brand is using Shimano parts, just realize and understand where those parts fall on the scale of quality. Many of the import bikes come with lower to mid-tier Shimano or SRAM components, but at least you can predictably service or replace those name-brand parts. Your service interval will likely be reduced, and yes you may need to perform more minor adjustments and tweaking, but there is no reason to run away from those products.
I would be cautious with mail-order bikes that don't identify the specific components, or use too many proprietary parts. Those potentially won't be serviceable in 5 years. Others using the lowest tier components likely won't make great high-mileage commuters as you will feel like it's always needing service, and the spare parts budget may be noticeably increased over time.
I certainly endorse the 'spend as much as you can afford' model, with the caveat that you have done the research to verify the bike and components are priced according to the quality. But don't be afraid of entry-level bikes if you truly cannot afford more. Just appreciate the limitations and trade-offs you must accept.