Sorry to be a buzz killer JKD as that was not my intention.
Your reason(s) for keeping your budget low are valid and prudent, as you are a student, most likely you are already over extended. However, you are in a good position having the Whites PRL-1 as you can hunt parks and Dry Sand. As long as you stay away from mineralized soil and Wet Sand at Salt Water Beaches, you should do well.
In my opinion, the best place to learn is in your back yard, if you have one, and then at a close by beach. I wrote this in a prior thread: Evolution of a shallow water hunter (Stage 1 from lawn to dry sand beach). I did not include parks as Hawaii only allows metal detecting at the beach.
The dry sand is the best and easiest place to hone your skills. First, you should focus on where people are as that is where you will find the most fresh drops. This is where you find the light silver and gold jewelry and clad coins before they sink below metal detecting depth. The time spent learning how to effectively treasure hunt in this domain is time well spent. I am talking about quality time of learning where to look, how to pin point, recover detected items, coil control, sweep speed, discrimination, trashy areas, work cuts etcetera, etcetera. This is the easiest place to learn and master skills that will be need for wet sand and shallow water hunting. Here is where you learn to be the hunter. The beach is vast while jewelry and coins are tiny. You have to know yourself, your capabilities and be committed to put the odds in your favor, before you can consistently find treasure. It takes time and effort to learn the above which should be master before hunting the more difficult wet sand then shallow water domains. I regret not buying an entry level detector to master these skills first as I wasted about one year of my warranty before I was ready. Your learning curve will probably be faster as hopefully you are open to alternatives and not set in your ways. " Old dogs take longer to learn New tricks".
Then there is karma which should never be taken for granted nor underestimated. The finds made by beginners with the cheapest of detectors on dry sand never cease to amaze me. I have seen newbie's find light gold and silver jewelry which look brand new - I even saw a newbie find a heavy platinum ring in soft dry sand, which is against all odds as it should of sunk like a rock.
As an alternative, You might consider allocating the amount of money that you are comfortable with spending toward metal detecting, rather than toward a detector, as this would give you more flexibility in purchasing stand up water scoops, finds bags, diving pin pointer, etc.
I would keep it if it worked well for me, but you could sell your White's metal detector through Members Classified on T Net or swap it for an underwater metal detector/equipment
If you do not customize and include diving, there are only two multifrequency VLF metal detectors with discrimination in production that I am aware of. The Minelab Excalibur II and the Fischer CZ21. So your odds of getting it right is one out of four. What? That does not compute! Four is correct as the search coils are hardwired and you have to choose between a 10 inch coil (wide field) and an 8 inch search coil (narrow field) which is actually 7 1/2 inch diameter on the Minelab. This is an important decision which you have to make. If I had to do it over again, I would of chosen the smaller coil as it easier to pinpoint with and is easier to use in strong currents . In Hawaii, you should never turn your back on a wave as you have to be agile and be ready to flee and survive.
As I have never seen or used a CZ21, I can only comment on what I have read. Norman Garnush, "THE GOLDENOLDE" preferred the CZ20 (earlier underwater model - CZ21 came later) over the Mine Lab Excalibur as he stated that he could cover more ground with its faster sweep speed. I have also read that it is good for finding larger rings deeper by other treasure hunters who use it. Which would be better for you would be determined by where you hunt, how you hunt, and what you prefer. I would not recommend one over the other, and would love to own both, as they have different tradeoffs.
. Im pretty determined also, while my buddies are out having a good time at a party, you can catch me out on the beach detecting. I recently got into the hobby due to my father coming home with a detector from an estate sale. He gave me a Whites PRL-1. Not really designed for the beach but I've been having some decent luck with the machine thus far on the dry and in some parks. Where I'm really looking to hunt is in wet sand and shallow water. The PRL can't get very close to the water lol, I'll go deaf. Honesty though you've made me reconsider and now Im convinced I rather save up, may take a while, but should be worth it. I'm very much interested in the CZ-21.
