The $400 price range for a pump is a really nice spot. You have a lot of options. You can get a used CCM S6 for that, save a little more and a S6.5 or T2 if you like half blocks. You can get a new Empire Sniper for that or a used one with the CheckIt kit on it. Both are very good options.
You can get a very nice Phantom for $300 and then have some cash left over to pick up other gear you need. I played with a phantom for a long time until I got my S6. Very solid guns, never had a bit of trouble out of it. Light, consistent and reliable.
Or you can build your own cocker pump, pick a body you like, get a nice pump kit, reg, internals, asa and barrel. The nice thing about the last option is you can make it YOUR gun, there may not be another one out there just like it.
I went the CCM route and could not be happier. I love my S6. But I know a few guys who are very happy with there E.S. One word of caution, the last option can turn into an obsession because of all the choices out there.
Just my 2 cents, hope it helps.