Hi AverageNova,
to IIS,
10" auto tracking dobbie for a first scope! Santa must think very highly of you!!
$300 to spend, I'd suggest these:
*GSO laser or cheshire collimating tool, the laser is a little easier to use with your size scope (from Andrews)
*GSO Superview 30mm 2" EP, at f/5, this is as long a focal length eyepiece as practical for your scope. Any longer and the shadow of the secondary can become too dominant. I have one of these EP's, great wide view EP until you have more to spend. It really is a good EP for this price. I have not seen anything to touch it until you dump $300 on an EP alone, and they also weigh a whole lot more too (from Andrews & Bintel)
*Meade Series 5000 5.5mm Plossl eyepiece. An excellent high power EP at a good price. It will be a much better proposition than a cheap barlow with a cheap eyepiece. Wider field of view, longer eyerelief, and much sharper image (from Bintel)
*The balance on an atlas ,The Cambridge Sky Atlas (Bintel) is excellent, or a planisphere. The Beginners forum has some sticky threads with fantastic links to planispheres and atlases. I've used these to print my own.
Use what you have first. These suggestions are for items I use. They do me fine.
Mental.