Best way to handle 301 redirects on a business directory

[Assemblo]

We work with quite a few sites that promote retail traders and feature a traders' directory with pages for each of the shops (around 500 listings in most cases). As retail strips, shops come and go all the time, so I get a lot of pages that are removed as the business is no longer present.

Currently I've been doing 301 redirects to the home page of the directory if you try to access a deleted trader page, but this means a ever growing htaccess file with thousands of 301 redirects. Are we handling this the best way or is there a better way to tackle this situation?