Hey Cody,
I found that joining a local club is a great way to learn "hands-on", because many members will be building a new layout, rebuilding a layout, adding to an existing layout, etc. You'll find the people involved in the hobby are very congenial, and they know that even they were at one time, new to the hobby. Plus, you'll make new friends in the process of learning.
As has been said, you have so many options for every phase of your new layout. I know that it's intimidating, but that's why we're here to help - local club members feel the same way. Buying gently used stuff is definitely the way to go. If you search around, nearly every region of the country has a train or a toy show where you can find a lot of these items. This forum is an excellent resource when searching the "For Sale" section. I've bought many items on the forum, and every time was a positive experience. Garage and estate sales are also a great source of finding train-related items at discounted prices. If you have a detailed and prioritized plan on what you're looking to buy, it's easier to stay within a budget. Model railroading is great fun and a relaxing hobby, and it can easily and successfully be done on a budget.
My train collection was all purchased one item at a time over the last three years. All items were bought in excellent to new-in-box condition, and most often at a small fraction of new prices. You have to really search, but the hunt can also be a ton of fun. Best of luck on your O Gauge journey. I know you can always find help on this forum from the incredible knowledge base of the members. Have fun, take it one step at a time, and soon, you'll be in command of your very own layout.
Tom