You can get a Sheridan Blue Streak for about $150, or the nickle plated Silver Streak for about $10-$15 more. These are in 5mm (.20) caliber and fire a very heavy for caliber pellet. Guns and pellets are available everywhere; it is a very popular rifle, and for good reason. It is the standard by which all other pump-up pellet rifles are measured.
I am somewhat of a gun nut, as most of you have probably gathered. In addition to my centerfire and rimfire guns, I have, and have had, quite a variety of air rifles. Everything from high-end match rifles for 10 meter competition to pre-charged pneumatics for pest shooting. I keep going back to my Sheridan, a 1962 model, that I literally found in a ditch under water when I was a kid. I dried it out, oiled it, and it has been shooting ever since. It will outlive me, and you cannot say that about many air rifles. Best value out there by far.
If you are really into it, you can even get a hot-rodded Sheridan from a company called Mac1 Air Guns. They have a web site; just google "Mac1 air gun". For $240 you can get their "Steroid Sheridan" that gives about half again the stock velocity, producing over double the energy compared to stock. These conversions are very highly respected in the air gun world. The basic, stock Sheridan is as well, for that matter.
Like I said in another thread, those of us that are into air guns, no matter how fancy, still reach for the Sheridan when things get "serious". As "serious" as things ever get with an air rifle, that is. Anyway, here is a picture of mine:
