How can I find a good UX designer if I am building a mobile app with limited resources?

It virtually depends on how quickly you want them and what skillset/enjoy you really need with a limited budget. I’d break up the approach into three areas:

A wild hunt:
With the aid of wild hunt, I imply browsing websites and attending activities in-person were the product designers generally tend to acquire. Examples of those are dribble, quora, twitter, Instagram, etc. Activities: local UX meetups (can locate on meetup. Com) and so forth. But this option is very risky as you will want to allocate a massive quantity of time and it’s now not a given that you’ll find what you’re searching out.

Strategic, yet manual targeting:
For this, I’d propose using LinkedIn search. You’ll be capable of filter out candidates by way of skillset, location, present-day employment reputation, and so on. Just like with the wild hunt choice - it’s volatile, time-ingesting and it’s not a given which you’ll discover what you’re seeking out.

Delegation of the above:
The likely only way could be to apply a hiring agency, that does all the above + uses it’s existing community and talent pool. The caveat right here is that it’s costly.

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Actually, if you have limited resources, there are many app-builder programs that have templated base apps for you to start with. You customize, add content and launch. I'm involved in building one right now for a client who needs to launch fast and cost-effectively for an event, and we are looking at using this same approach.
While they may not get you all the bells and whistles you want, it's a great way to do a proof of concept or support for an event. Later, you can look to hire a development team to expand on what you've started.
A good place to go to find support is Upwork or other freelance sites like this. Upwork shows other jobs and reviews.
Hope this was helpful - feel free to reach out to me for more help here!
-JL

Use Upwork or Fiverr. You can also use programs like Proto.io to design it yourself.