I now have three tenants that have broken their leases and vacated their apartments leaving me with approximately $5K in uncollected rents. I know I can proceed legally towards judgements, the cost of which gets me to just over break even and i still wouldn't have any cash for my efforts.

Does anyone have experience with other approaches such as collection companies or selling accounts receivables

Thank for any help that you can provide

Typically in this situation you won’t get that money back. Best way is to screen better and not let them get behind on rent and evict when it happens

I may be wrong, but I'd be surprised if a collection company would buy a debt that isn't reduced to judgment.  If they buy a judgment, they can go directly after the debtors bank accounts etc... (which is difficult enough) Until they get a judgment, they have a legal battle, not something they can collect.  That added risk means they'll pay less.

Pursuing tenants who have vacated is usually break even at best.  Call it tuition and move on.