This isn't an easy question. The price difference does mean something. But does it mean you should go with the more expensive product?
Public defenders can be a special case. They may be young individuals seeking trial experience, who now have a few years or more under their belts and may be leaving shortly. They may have a ton of experience with your kind of case, know the players involved, and can work the case extremely well.
Then again, they may also be completely overloaded, lacking in experience, unable to find a job elsewhere for professional reasons, and so forth.
With a public defender, you'd want to ask how much experience they have with your kind of case; how many hours each week your case would likely require to handle with maximum effect; what kind of caseload they have, and how many hours they're already working per week on other cases; how long they've been a public defender, and why. Do not be shy.
With any other criminal lawyer, you'd want to ask similar questions. An inexpensive lawyer may mean a very competent, effective lawyer who is still somewhat new, and therefore without a large and reliable client base which would allow him to raise his rates. He may be especially enthusiastic, since he's building a practice, and he may be able to give you better representation than a more expensive lawyer. You'd still want to know he has good experience with criminal cases, and with YOUR type of criminal case, and you will want to know his prior professional experience (did he ever work at a firm or as a prosecutor, or public defender; did he clerk for a judge; etc.). Or he may be a lawyer whose practice is based on relatively simple cases, with which he has a lot of experience, but also where there is much more competition from other lawyers, driving down his rates; or the clientele who require services in such cases may simply be unable, for the most part, to pay much above a certain fee.
An expensive lawyer means that he has a reliable client base who can and are willing to pay his rates. This in itself is an indicator of competence and experience, but you'd want to ask the same questions you asked of the less expensive lawyers. However, his price may also reflect that he generally handles very complex cases, which may not be like your case at all, or that he's plugged into a good network of wealthy clients, doesn't handle all that many cases, but is trusted by people in that network, and so gets business sufficient to sustain his price.
My best advice to you is to ask questions. You'd need to make a decision rapidly, and so you'd want to have questions ready, and to be ready to make a decision quickly. But you've got to elicit information first, and the price isn't enough because it can mean different things.
Also: ask the lawyer what HE would ask before deciding on counsel. Listen carefully to his suggestions, see if there's anything you agree or disagree with, add anything useful to your list, and, if he's suggested something you haven't asked him yet, then ask him (he'll be waiting for it).
So, make up a list of questions. Ask, ask, ask. Write down answers. ASK for suggestions for choosing a lawyer. Write down those answers too.
And then, quickly, make a decision. This is a game where you're very constrained by time, and so you'll need to move on whatever information you can gather in that time.
The good news is that, as long as you pay attention, and as long as you give yourself SOME options, you'll almost certainly end up with competent counsel.
Final word:
Felonies can have a deep and long-lasting impact on your career choices going forward, and can require you to overcome substantial future obstacles that would not exist but for a felony conviction. A good lawyer, even if it turns out to be an expensive one, is worth it, given the stakes.