I am building a bot that until recently was EXTREMELY similar to Shark Beetle. When I was shopping for parts for my bot I was told on this forum that the motors on RobotMarketPlace have been listed as backordered for a few years now, so I wouldn't hold your breath there. In my search I did find two motors that looked to be quite similar to the B16 motors on RobotMarketPlace, and KitBots should still have some mounting plates left for the B16 motors:https://www.servocity.com/html/730_rpm_precision_planetary_ge.htmlhttp://www.shop.rovparts.com/22mm-12v-DC-Gear-Motor-780-RPM-RP-GM-22-12V780.htmhttp://www.kitbots.com/product.sc;jsessionid=FBAF480DBDF1416245F7D08554D1C113.m1plqscsfapp04?productId=14&categoryId=1
Having said all of that, the 1000rpm motors from KitBots have a long history of surviving beetleweight competition as well as having a metal front plate you are mounting to, while the other motors haven't been around enough to hear whether they'll survive fights, they have plastic front plates you are mounting to that could break easier, and they are significantly more expensive. Personally, when I was faced with the choice I went with the 1000rpm motors. You could either contact KitBots to ask when they might have the motors back in stock, or it looks like RobotMarketPlace might have the KitBots motors in stock for a little bit extra:https://www.kitbots.com/contactus.schttp://www.robotmarketplace.com/products/KB-1000RPM.html
For the ESCs it looks like Shark Beetle was a Trilobite kit, and it looks like the kit used four of the BotBitz 10A ESCs:http://ttrobotics.com/botbitz-10amp-esc/
Those ESCs should work for up to a 3S LiPo battery. I wanted more speed/power, so I had to find ESCs that could take the voltage of a 4S LiPo battery, and I settled on two of the RobotPower Wasp ESCs:http://www.robotmarketplace.com/products/0-WASP.html
The two that got shipped to me seem to be defective out of the box and have already burned out one of my motors, so I'd say you buy those at your own risk. I have been trying for weeks now to get a refund/replacement on mine.
Before I changed to a two-wheeled design I was planning on switching to four of the FingerTech tinyESCs:http://www.fingertechrobotics.com/proddetail.php?prod=ft-tinyESCv2
You might be able to find some other options out there, these are just what I came up with when I was shopping for parts for my bot a little while ago.
I hope this helps!