It's less than a stock background costs, and less than the work would cost to recreate it yourself.

Googling "polygon background generator" will get you a dozen free or ad-supported ones.

If it were $1, you still wouldn't buy it.

The customers who are this price sensitive are always the worst. They're the most needy, and the most likely to churn.

When a contract is $50,000 all you ever hear from the client is "Invoice paid. Thanks!".

What's your hourly rate as a designer, and how many minutes would it take to put together all the triangles in Illustrator?

If you make more than $16/hr and it would take you 30 minutes to put this together triangle-by-triangle, color-swatch-by-color-swatch, then $8 is not too much, correct?

Not just that... If he has to do any kind of customer support it rapidly becomes a money losing business at $1. Looks like it wasn't worth it at $4 either.

I don't know you, so I'm just making this up, so given that preamble.

No you wouldn't.

Inflation