A really good espresso machine that makes wonderful coffee out of quality beans will easily cost a good grand. At good coffee shops the 3-5 head machines will easily cost $20,000-$50,000.
If you want a 'good' cup of espresso at home, i think its basically a crap-shoot with little correlation to cost; and very different responses to different beans and grinds (again not correlated with cost). I, for instance, have a Mr. Coffee (piece-of-junk) single cup, half-plastic, machine that I got at a garage sale for about 10 bucks (probably cost about 40-50 new), and with really cheap cosco coffee, ground course it tastes GREAT.
The moral of my story is, if you want to be O.G. go for the $500-$700 ones, or consider a classic piston driven type. Otherwise, if you're just looking to get the job done, considering getting 2or3 low cost version, and trying a dozen different types of coffees and grinds.
Best of luck, you'll need it