Muhammad, Eclipse doesn't have J2EE support or a server. You can't accomplish what you can do in RAD with just Eclipse. There are cheaper/free options for both: J2EE support - the inexpensive MyEclipse (which we just ran a promo for) or Eclipse's free J2EE tooling Server - Tomcat or JBoss - both free
The advantages of RAD are that you are deploying to an actual WebSphere server. Which means you won't be suprised by WebSphere bugs later in the process. I presume you are planning to deploy to WebSphere eventually? (If not, there is no reason to consider RAD.) When weighing the cost of RAD, be sure to compare all the time spent later because WebSphere was not available earlier in the development process.
One thing that jumped out at me is that you are considering this because you are outsourcing. Which implies your in-house developers use RAD. Is there a reason you don't want your outsourced developers to use the same tooling? Presumably you want them to be as productive as your inhouse ones.