Great question, Matthew. Quickbooks Online is very affordable. I'm not sure where you got your information but it's not into the thousands. One QB Plus subscription will cost you about $65/mo. And 3% bookkeeping fee? Who have you been talking too? LOL!! That's not always feasible to a small business, I have to agree. But there are accoutning firms out there that charge a fair price and one that won't kill the bank. Something you might want to consider is what is it going to cost you in the long run if you're doing your own books? An accountant knows and follows the laws and standards and can help you maximize your profits and save your thousands. Way more that what you might spend on a monthly basis. All you have to do is budget that bookkeeping and subscription expense. I do have to disagree with you on the one size fits all. I have clients that gross well into the tens of millions, they hold residential and commercial properties. QB has never been an issue. You just have to know how to use it.
When you purchase something at Lowe's, the cashier usually asks if there is a PO. If they don't, you can tell them and it will print out on your receipt. The PO should be the property address. Then when you email that receipt into your QB account, you or your bookkeeper will see the printed receipt with the PO and can categorize that expense to the right property. Any other receipt? You can simply write the property address on it then take a photo and upload to your Quickbooks account. Any digital receipts can be emailed right into Quickbooks.
I have heard of Baselane and actually have met with one of the owners and developers. I haven't used it yet but from what they've shown me, it looks real promising and maybe worth the time trying out.
There are many receipt bank type softwares available. I can't suggest one b/c I don't have any good experiences with them. You may find one that suits you if you keep looking. I would certainly schedule the same time every month to take care of your finances. Make it a discipline if you haven't already. You'll soon find out what works for you and what doesn't. All the best!