Will your client come back later and ask for status?
Is JMS too complex for simple situations.
As for expense, The Sun Application Server is free and has a JMS server.
If you are a developer you can build an application with the J2EE 1.4 SDK and then deploy it on the Sun Java System Application Server Platform Edition 8 (included with the J2EE 1.4 SDK or available separately). No matter how many developers are on your team, all of them can use the J2EE 1.4 SDK at no charge. Once your application is ready for production, you can deploy including the Sun Java System Application Server Platform 8 Edition in production on as many servers or CPUs as you want.