Hi edare, and welcome to the world of audio!
It's not true that you need an external sound card vs internal. They actually both have their strengths and weaknesses. For example, an internal sound card might have lower latency than an external sound card, as the distance/cable related to an external card typically means it takes longer for the signal to travel from your sound card to your DAW (AKA the software you use for recording music). You can read a bit more info about it
here.
However, if you get a cheap external sound card, then chances are you get what you pay for.
In general, to avoid crackles and pops (provided that you aren't using resource-intensive instruments, effects or plug-ins), you can find a quality entry-level interface for around 100 bucks brand new, or even cheaper if you buy used (try searching in
our classifieds section).
I'm no expert on audio gear, but in general, if your budget is around $100-$150, then the cheapest audio interface you can buy that will likely fit your needs are:
There are other interfaces that are certainly better, and sometimes you can find an amazing deal (for example, my first interface when I decided to get more serious with recording music was the
TC Electronic Impact Twin. Normally these cost more than 300 bucks, but I bought mine for around 180).
However, if you want to spend less than 200 bucks, and are serious about wanting to record the best audio you can within this budget, then you can't go wrong with the above 4 interfaces. If you want, use the price slider on Audiofanzine to find any other deals. For example,
here's a link to all external audio interfaces under $206, available through one of our retailer partners. If you're based in Europe,
here's a list of all interfaces available for under 205 € (accessible on the french version of Audiofanzine).
Hope that helps