Selfhosting

@iocase With 20 employees, you'll probably want to look at open source solutions unless you have a significant budget available. To get all your employees on Microsoft Dynamics Nav, for instance, would run about $8000 a month.

The drawback of open source solutions is that you'll likely need a dedicated employee to keep the system running and updated, and there's no higher levels of paid support option if they run into problems.

Here's a pretty good article on using Quickbooks as a core and then attaching open source Inventory Management and CRM integrations that you may find useful.

@iocase If you need something simple (inventory, billing, sales) try Dolibarr. If you need something more complete, try something like Tryton (Odoo 8 fork).

I do not reccommend Odoo, as the community version has limitations and you need a subscription un orden to use all the modules.

I would take a look at ERPNext, the pricing page shows $0 for the open-source version with all features: https://erpnext.com/pricing

As mentioned by others, you'll need someone to set it up properly and maintain the software as it will likely become a core part of your business if utilized properly

For a small business with diverse needs, an ERP system that can be self-hosted and integrates with QuickBooks desktop would be ideal. Here are some good options:

1. Odoo: An open-source ERP system with extensive customization options. It can be self-hosted and integrates well with QuickBooks through third-party modules. It supports custom invoicing and dispatch functionalities.
2. ERPNext: Another open-source ERP system that allows self-hosting and provides modules for accounting, project management, and inventory. It offers integration with QuickBooks and customizable invoice formats.
3. Dolibarr: A self-hosted ERP and CRM solution that is user-friendly and can be tailored to specific needs, including custom invoicing and dispatch management. It can be integrated with QuickBooks through available connectors.
4. xTuple: Offers a self-hosted ERP system with capabilities for manufacturing, distribution, and accounting. It provides integration with QuickBooks and customizable invoicing options.

These ERP systems can help manage job scopes, skillsets, and equipment while ensuring compliance with your self-hosting requirements.You can also read this for more options.