Hi, and welcome to the forum
In my opinion it will cost you around $300 minimum to get started with a new entry-level detector (ACE 250 or 350, $200-$300, plus lesche or other digger and pinpointer, $50-$100). You have experience with detecting and already have sites in mind to detect, which indicates that you know this will be a hobby you are likely to stick with.
Many (not all, but many) people who start with an entry-level machine like the ACE 250/350 series end up upgrading within a few weeks or months to a higher level machine. Many start out with the Garrett ACE series (or comparable machines by other manufacturers) because they have a tight budget and/or because they are not sure that the hobby is really something they will continue to invest time in. If they continue with the hobby, then they frequently upgrade.
It is hard to describe the differences between an entry-level machine and a higher level one to someone who has not experienced the process. Usually people will just say the more expensive machines have more bells and whistles which is true, but doesn't really capture the true essence of the reason. Most people (myself included) who started with the ACE250 go through the detecting learning curve with that machine until the limitations of the machine become clear to them, and become an issue in their detecting.
In my opinion the entry level machines like the ones I mentioned above are great coinshooters. One limitation is that most do not have the capacity for ground balancing which results in falsing in ground which is mineralized unless the sensitivity is reduced (resulting in loss of depth). Another limitation, at least with the ACE, is the lack of volume control related to target depth (all signals are the same volume regardless of depth). The main limitation, though (which captures the things I listed above, as well as other factors) is that there is just less information that the machine is capable of telling you about the target under the coil - compared to higher-end machines.
This doesn't mean that it is easier to find good targets with a higher end machine. This is a mistake that many people new to the hobby make. Even some detectorists not so new to the hobby may tend to make this mistake, and think that upgrading to a higher end machine will almost instantly result in better finds. This can lead to disappointment, because it is a process to learn what ALL detectors are communicating regarding the target under the coil. It is frequently even more of a learning curve to understand what a higher-end machine is telling you about the target, as compared with a machine with less features - that is, if you want to put the time in to really, truly, know and understand the machine. The detectorists here and on other forums who consistently pull silver coins from hunted-out areas do so because they know their machines extremely well.
So the big difference is that higher-end machines are capable of giving you more information about a target, including in some cases, incredibly subtle or iffy information about very deep targets or those good targets that are buried among trash or iron. Most any detector will pick up a coin or other desirable target at a relatively shallow depth (5 inches or less) which isn't surrounded by other metal, and will be relatively accurate in identifying it as a coin. The reality is that, at least in public places that have been detected previously over many years, the good targets that are still in the ground tend to be VERY deep, or else mixed in trash and therefore give iffy or bad signals that do not prompt the detectorist to dig. This is where the higher-end detectors excel, as far as I'm concerned. But again, it requires that the user really understand the machine.
So having said all of that, think about what kinds of sites you have and what kinds of sites you want to detect in the future. Think too about whether you are interested in finding relics (iron) or if you are mainly just looking for coins or silver. Or gold.
There are a lot of differences even between mid-range and high-end detectors, such as multi-tones (some detectors use only one tone - eg, White's MXT - whereas others allow for multiple tones to be used to match to the conductivity of the target), whether or not you want a visual/digital meter or only want to rely on sound, etc. Some of those things you probably will not know the answer to until after you are further into the hobby. An advantage of most higher-end detectors is they allow the option for such features if you want to use them.
So rather than suggest a specific detector (everyone has their personal favorites), those are some things to think about. Given your budget and previous detecting experience, and the likelihood that you will remain engaged with this hobby, I would suggest at least a mid-range machine for you.
No matter which machine you choose, be prepared to spend a lot of time learning what it is telling you. It's worth it. :yes: