Congrat's on your potential new venture!
I considered opening a drum shop several years ago but decided against it due to other obligations.
Drum, cymbal, and some hardware companies have made it a lot easier by allowing rotating inventories or "touring inventories." Essentially they send you a bundle of gear for a scheduled period of time, whatever doesn't sell, goes back to the distributor. You pay for what you sell or want to keep in-store, and then get fresh new inventory sent out when the unsold gear is returned to the dist./manufacturer. There are credit worthiness requirements, not all companies do this, and each that do will have different procedures for it.
Overhead expenses such as retail space can be reduced by working with a local business incubator that has space available. Extensive and cost-laden leases aren't needed nowadays*
If Badges Drum Shop (Mason, OH) and The Cymbal House (Covington, KY) weren't by me, I'd be giving serious reconsideration to opening an instrument shop now. My perspective is that it's a "buyers market" for those looking to lock-in low cost business operations.
*two REITs I work with aren't accepting new money for their Retail space funds due to a glut of it available now.