The most fun way to get into tube amps is, by far, a repurposed Magnavox console amp. 6V6 and EL84 P-P amps are common and cheap. You can get your feet wet, have fun with mods, roll tubes, etc. for lots less than $500, with a willing market to buy it back if you don't like, or want to upgrade. I'd put the Dynaco ST-70 as your #2 tube amp to own, once you know you like them and want to get serious, as it's much more costly to get decent EL34's as it is EL84's. Plus now you have a 5AR4 to consider, a good one runs the best part of $100 for an early 60's Mullard or Amperex. Rarely do the cheap ST-70's come with decent(or any!) tubes. Having bookshelf Klipsch speakers overcomes one of the hard parts of owning a small watt amp, high efficiency. I, also, recommend getting the membership necessary to buy and sell in Barter Town. It's a well spent $25.00!
Good luck!