Don't let the price tag depress you, the location you hunt is the most important factor, not how much money your machine is worth. They all detect metal, but it has to be in the ground in the first place. Sometimes discrimination is your best friend either, it just convinces you not to dig stuff, when you don't feel like digging much. No detector can tell you 100% what's in the ground. People have been hitting the same old sites, for decades, and still finding old stuff, silver coins. Lot of people running very expensive machines, still picking stuff up, where they've been hunting for years.
We don't find post-worthy stuff every hunt. My last few hunts, only two zinc pennies, lots of iron stuff (pipe fittings mostly), some brass. Not worth taking pictures, or getting excited over.
Couple of good places to start, are your own yard, and family owned yards, permission pretty much guarantied, plus you get some practice digging pretty holes, filling them in nice. You don't really want to tear up your own yard, but the owner is very forgiving as you learn. Out in public places, it's an important skill, if you want to go back and hunt. A good transition from your yard, to public land, is the grassy medians, a strip of grass between the curb and sidewalks. Those sidewalk strips are usually owned by the property owner, but the city has the right to dig them up, utilities are allowed to use them too. Most homeowners just keep them mowed, and accept that they are part of the right-of-way.