I like that hand pump quite a lot, I take it with me when I go play, but I use my 6 year old Yong Heng compressor to fill beforehand as it's easy and a little faster.
You can get into HPA if you use an AliExpress regulator, make an air line out of AliExpress HPA fittings and air line, and don't get a dumb engine. The N7 and Mancraft engines are good and cheap, with the Jack being the next best engine. The Wolverine engines, F1, F2, and Fusion aren't really worth it unless you can get them cheap, but buying a used engine can be a bit of a gamble sometimes, especially when you get it from a younger person who plays speedsoft, as their engines tend to have been bought used a couple times before you do. But yeah, say $250 for a Mancraft shipped, don't remember the exact price, but close. Air line can be had for $15 or so if you just use normal line and cheap fittings, and an okay tank can be had for $60. Get aluminum, definitely don't get steel. Regulator is another $45 on AliExpress, and there you are, HPA setup for $370 without buying used. You won't have full auto, but that's really not a big con when your trigger isn't connected to a motor. Compare that to a decent MOSFET, gears, piston, motor, cylinder, cylinder head, nozzle, batteries, charger, and whatever else, and you're not far, or maybe even over depending on what you get. You can pay $500 for a setup all at once, or $500 over a longer period of time, and have a $500 AEG that will very likely not be as good as the HPA gun.
As for high end builds, you can max out both, but the HPA may actually be cheaper if you have your senses about you and don't buy a Fusion Engine or Wolverine engine, and don't get a Retro Arms gearbox to hold your engine.
I've come to realize that it's difficult to get into airsoft and have a good time for less than $400 after helping my friend start, as there's so many bad guns and batteries you can buy, and most guns I've used just kind of suck to use. Not saying HPA is better, but airsoft isn't as cheap as people make it out to be if you need to buy mags, gear, charger, batteries, BBs, field fee, gas, and all that. May be hard to hear for some, but it's better than spending $150 on a sniper and then never playing again, and having wasted $150 plus whatever else you spent.