You CAN start out with an entry level ESTIM power supply for 20 or 30 dollars perhaps, but trust me - once you get into it, you are going to wind up wanting the ZEUS 6 channel. Several major points make this a BUY: 1) SIX separate 2.5mm outputs - this is the standard TENS size so if you have a standard TENS wire or accessory, it will fit. Each of the 6 can be independently controlled, turned on or off and set to any intensity you wish by turning its knob. 2) AC adapter is included - NO ONE wants batteries to die on you as you are crossing the finish line 3) The timer can be set to run up to 70 minutes - that is just over a full HOUR. Many lesser units limit you to 15 minutes, and restarting every 15 minutes is a royal buzz kill. 4) ZEUS includes a full YEAR warranty which isn't mentioned in the listing or by the sellers but should be 5) I also want to mention that many of the negative reviews here complain because, according to them, you go from tingling to pain too quickly in the upper range of each knob. This is actually a very common complaint amongst all ESTIM users, no matter the power source. There is a very FINE line between pleasure and pain, AND the conductivity of your skin can vary greatly from one small point to another, so, it is inevitable if you are going to play with ESTIM you will occasionally get a jolt, but it will not kill you and it will make you appreciate the pleasure point all the more. Remember John Cougar's song HURTS SO GOOD? ESTIM fits right in to that harmonic frame of mind. If you are new to ESTIM, buy this baby as your power source and you will NEVER feel slighted. Just remember 2 golden rules - keep all the electrodes below your waist level for safety, and do not TOUCH any of them with your hands while they are running - if you want to move one, turn it off first. You will get a nasty shock if you touch one while it is on, even if it feels like next to nothing where you have it attached to your skin. In terms of accessories, I HIGHLY recommend, for gentlemen, trying all the various sizes of anal electrodes, as these will come into direct contact with your prostate gland if you use them right. The conductive rubber cock loops are also SUPERB - one near the tip and one at the base for most unearthly results. Also, play around along the inner length of your thighs, there are some really interesting sensations to be had there, as well as the bottom of your feet, of all places:) The only downside I can see to this box is it is HIGHLY addictive, and I will more than likely wind up owing mine alimony. Took off ONE STAR because I find the variety of wave patterns lacking in diversity. This $30 TENS UNIT http://www.amazon.com/gp/product/B007TOJ948/ actually has far better and more diverse choices in wave patterns, but is tragically hobbled by its 15 minute limit.