Hello everyone. I apologize if this is the wrong section. I’ve been tinkering around a bit with an Electron and some various breakout boards to prototype a product I’d like. I’m at the point where I think I have a good idea of what components I’d like to see in a finished product. I’ve never designed hardware before and aren’t really sure how everything should go together (e.g. if I had ‘component 1’ do I need a certain resistor or capacitor or something). I’ve been a software developer for 15+ years and this little project has been my first jump into hardware. I’m not even sure if it would end up being something anyone other than myself would use. But I’d like to see if I can get it all together in a small, single package and see if I can make it work. It doesn’t necessarily need to use an Electron as a base, but if it didn’t, I’d still probably use the the same chip and cellular and flash it with the Particle firmware, as I like how it all works. I’m not sure if I’d save any size/space at all by going totally custom, or if I just had maybe a shield with the rest designed? So I’m wondering what some resources there are out there to help in designing a custom board? If I say “this is the MCU, use this component, this chip, etc” and have someone help me get it all together. I’m not really sure even where to begin. I’ve seen quotes of $10,000 for design/prototype service or as low as a few hundred dollars on sites like Fiverr. Since this is all foreign to me, I don’t want to go investing money into something that’s totally wrong. Especially if it’s something that I’ll never get a return on. Any advice/help is appreciated. Thanks.
Wow, you're going to dive of a cliff here ... but that can be fun 
Getting a bit of custom hardware together requires:
a. A schematic
b. A board layout
c. Ordering the board & parts.
All require specialized knowledge but if your design isn't big and "special", this might not be a huge barrier.
There is a variety of schematic capture/board design software that is free and that will accommodate small designs. Some get you going quickly but have limitations for larger designs, others require some reading/studying of the domain to know what you need to do.
To get going quickly: upverter.com is not bad. Nothing to install, free use of the tools but a bit of a quirky interface and some other snags.
Much bigger/better are: KiCAD or Eagle. These are both installed on your Win/Mac, KiCAD has no limitations Eagle has some max board size and layers limitations but for small designs not an issue.
There are a ton more but this should get you going. Note that these softwares require you to know the components, how to set up the board design rules etc.
For part ordering in the USA, Mouser and Digikey are well known (or AVNet if you're a bit bigger :-). Boards can be ordered from OSH Park for a reasonable price and lead time but there are asian manufacturers that are cheaper (but take more time).
I know I have just lightly covered the possible answers to your question but hopefully this gets you going.
Thanks, I’ll take a look at the places you mentioned. I was also curious if there were any people/places that offer assistance/consulting on such things. Either as a 1-time thing or as someone that may be interested in partnering with me.
Happy to discuss and give some inputs. 
You can post your questions here or drop me a private message.