I could use any argument I like

His followup:

Hi PrisonIndustry,

Have you had a chance to look at our proposal? When do you think you might be purchasing?
Please let me know.

Thanks for choosing [vendor name]

My response:

Hi Vendor,

I've had a chance to look at it but I'm currently waiting on final approval from my boss. I think it's out of our budget for the time being however. If I get the go ahead I will be in contact with you to order.
Thanks,
PrisonIndustry

His final reply:

Hi PrisonIndustry

Just a suggestion,

You could use the argument, that with the current state of technology, you can’t afford not to.
Thanks for the information.

Since I was asking for a quote for Office licenses for a school, I'd say the current state of technology has nothing to do with it.