The phrase 'upon request' is correct and is commonly used in written English. It is used to refer to something that will be done or supplied if someone asks for it. For example: We can provide additional information upon request.
Pets upon request.
Painkillers are available upon request".
Price upon request at sjphillips.com.
Pricing is all upon request.
I sang songs upon request.
Flights arranged upon request.
Headshots available upon request.
When I feel like I can't trust my brain 100%, Ludwig really comes in handy. It makes me translate and proofread faster and my output more reliable.
Claudia Letizia
Head Translator and Proofreader @ organictranslations.eu