Inventory management is one of those balancing acts that even the most experienced dealers wrestle with all the time. In fact, the popularity of closeout stores like TJMaxx/HomeGoods, Ross and others should show you just how tough it is to judge what kind and how much merchandise customers really want.
Those stores are filled with professional retail buyers mistakes. I wouldn't be surprised if those mistakes were made when the buyer was desperate to fill the shelves of whatever store he or she works for.
Inventory Management in an Antique Mall
I'll cut right to the chase with the main point I want to drill into your head: Don't buy any old thing just to fill your booth. No, no, no - never do that. I'd rather see a sparsely stocked booth with fabulous merchandise, than a booth stuffed to the gills with placeholder crap.
It's common for brand new booths owned by brand new dealers to be on a bit the sparse side. And, you know what? That's okay. Work on styling the merchandise and space so well that it looks like you planned the spareness. Call it minimalist, if you must ;) Eventually, you'll amass enough good merchandise to fill your booth a few times over.
Having enough inventory to refill your booth at least once is a good beginner goal. Once you have that much inventory in the wings, you can become even more selective in your buying.
Dry Spells and Rolls
Take advantage of those times you're on a roll - when the merchandise you're finding is great and the prices are even better. Chances are that those phases will be balanced out by dry spells when you can't find anything worthy for your booth no matter how much you dig.
You'll be tempted during dry spells to buy anyway. Don't. Again, never buy placeholder stuff for your booth. Just save your inventory budget for when the good merchandise starts flowing again. And it will flow again.
How much stuff should you physically stock in your booth?
A good guide to follow is whether a customer can reach out to touch every item in your booth without fear of breaking something else. I wrote a quick post on how I feel about badly styled booths on Indiepreneur. Even chandeliers should be low enough so that customers can see the details, even if they have to ask for help getting it down when they're ready to buy.
Making room for your customers in your booth doesn't mean that you can't pack in a lot of product. It all comes down to styling and using your square footage effectively.