I saw Matt Rini daughter ski and he gave me the idea to make my daughter a Pro quality ski. I took a 65" Radar MPD blem and made a 61" out of it. Works terrific and she loves it. She was 9 when I did it and is now 12 and ripping on it, full width course 6 balls @ 25 mph.
Bought the blem for $100.00 and cut 4" off the back end and moved all the inserts and fin forward proportionally. I can walk you through it and have pictures taken at stages of the modification. She has a 61" custom Radar ski that rips and is turning heads at the tourny's.
After cutting off 1/2" of the rounded edge tail with my skill saw, I then used the skill saw to lengthen the fin slot by 4". Then I measured 4" up from the most forward fin box insert and matched the hole pattern. Then I measured up the edges 4" from the cut off tail and drew a straight line across the width and used the skill saw to take that 4" piece off. Eddie Roberts sent me a bunch of the SS inserts they use, so I just installed them and mounted the fin box. I split, spread and attached with epoxy, the 1/2" factory molded tail section to finish off the tail. Used epoxy putty as bondo to smooth out the tail so it is as close to factory shape and contour as possible, then a bit of flat black spray paint and it looks fabulous. Then Matt Rini helped me calculate the boot inserts locations which worked out great. Mounted up some HO junior bindings and the finished ski looks like a factory fresh Radar MPD miniture.
Years ago, I bought a used HO Odesey for about a $100. I has a sort of a v-bottom to it and is very stable. I'm quite sure it's a 63", could be a 61". It's a ladies ski, with a softer flex than the men's version (Comp Freeride I believe). Thankfully it has pretty cool graphics that don't look girlish, as my three boys all started slalom with that ski. My youngest uses it now, is a 9-year old, 4'10", 105 lbs and a bit of a bull. He can do the mini-course on it at 25 mph, even though I'm sure the ski is a couple inches longer than needed. His older brothers used it until they were skiing about 28 mph. So the ski has a lot of mileage on it, and my wife uses it too sometimes. Easily the best $100 I've ever spent on waterskiing. I put on double HO shock bindings, which aren't too expensive, are easy for a kid to get on and off (critical feature), and also accommodate feet that are growing about 2 sizes a year! I think the HO Judge is a kids slalom you also might want to look at, with a more traditional bottom design. Have fun!