Don't buy things that are part of your core business. (If your business is creating a word processor, don't buy a rich text box control) Do buy things that are

Don't buy things that are part of your core business. (If your business is creating a word processor, don't buy a rich text box control) Do buy things that are commodities and outside of your domain specific expertise. Accounting software (assuming you aren't an accounting software company). CRM software. Rich text controls. Build things that give you a competitive advantage over other companies in your sector.