Ask HN: Does my company with $140,000 annual revenue have any value?

I am a 21-year-old web developer who operates a company (incorporated) with a couple unique web apps relating to website management and ecommerce. The software is downloaded and hosted by customers (not SaaS) but uses licensing and encoding technology so that sharing the code has not been a problem.

Licenses for the software bring in around $35,000 per year, while related custom development by myself brings in around $110,000 a year at a $150-$250 per hour rate. I work part-time, take vacations, etc. Bottom line: It's a great job with great clients and I couldn't ask for much more at 21-years-old.

However, I have just graduated with a degree in a field of research that I want to pursue with grad school. My plan is to sell the business in a year and move on to graduate school.

But is there any value in this business? Will other web development companies see value in acquiring my clients, products, and websites? There's little money to be made without work: I would predict $25,000 per year could be made without answering any emails or doing anything. However, if a company or person kept up with sales/support and doing custom development, they could easily make $200,000 in a year.

What do you think? Am I just trying to sell a full-time job or is there value in this business?