Ah, the 3G requirement seriously limits your options (HP Touchpad $99 in B&H RIGHT NOW, as well as plenty of excellent sub-$200 android tabs).
The HTC Flyer is pretty excellent, as is the Galaxy Tab 10- but with options like the Moto Xoom almost the same price as an iPad, it begs to question why bother if you already like Apple's product.
If you just want an inexpensive 3G tablet to get your feet wet, the 7" Galaxy Tab is relatively cheap this days. However the hardware is aging on that already. If you don't need 3G, a world of opportunity opens up to you.
I personally love the Nook Color and ViewSonic G-Tablet, with my personal tab being the Viewsonic (Tegra 2 dual core for $250? Yes please!), and would even recommend the TouchPad if you can find one in stock.