Completely "Restored" is a term that is used very loosely amongst builders and greatly affects what the total "Worth" is. When someone says "The only thing that's not original is...", then it's "Not" completely restored to its "Original" condition now is it?. This being said, if someones said it's "Worth" $4,500.00 and you went out and spent that on it only to find out that all the high dollar parts that make it "Worth" $4,500.00 were missing, you'd be pretty mad. These were also sold under the Sears name, someone could have taken a Sears bike and altered it to a Dart bike which may or may not affect value but if you found it was altered after someone told you it was original, again, you would be pretty upset. The first thing I look at when considering a "Restored" bike are the tires. Period correct tires are one of the hardest things to get seeing how they are the most consumable item that is no longer being produced. For example, a period correct set of NOS Goodyear tires for this bike will cost you about $350-$400 while a fresh set from the hardware store cost $50. When considering any big purchase that you are unfamiliar with, take lots of detailed pictures, ask questions, especially to the seller. If the seller says "It's worth $4,500.00", ask him/her "What makes it worth that much?. Then do a lot of research on those particular items. To serious collectors, it's all about the smalls, these are the things that set apart a truly "Restored" bike. Take for instance, someone is selling a Lil Indian mini bike and claims it to have the original brake caliper. Is it original to the bike? or an original part?, is it period correct?. There are many different variances of calipers offered throughout a models history, they all fit/function the same but it may not be the period correct part.
As for the rule of not giving "Values", the biggest reason I would say this rule exists is to keep people who are serious about the hobby here rather than people just using up members time so someone could get a benchmark "Worth" so they could list it for sale, never to be seen or heard from again. Hopefully you do stick around, if your first interest is this Dart Cycle, you have exceptional taste in mini bikes and get my vote!. Good luck, welcome to the site and most of all, have fun!.
-A2M