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but to me that seems like overkill and makes the code a little bit harder to understand.

I'm not sure but I think you may be asking how to both protect against bash globbing, etc. constructs and ERE metachars so you can create a regexp that includes parts to be treated literally. If so:

• Store the regexp in a variable to have bash metachars treated literally (see How does storing the regular expression in a shell variable avoid problems with quoting characters that are special to the shell? for an explanation of that) and
• Escape the ERE metachars in the variable (see https://stackoverflow.com/questions/29613304/is-it-possible-to-escape-regex-metacharacters-reliably-with-sed which describes the same problem for sed, just apply the same solution using bash parameter substitution).

I'm not sure but I think you may be asking how to both protect against bash globbing, word splitting, etc. constructs and ERE metachars so you can create a regexp that includes parts to be treated literally. If so:

• Store the regexp in a variable to have bash metachars treated literally and not cause word splitting (see How does storing the regular expression in a shell variable avoid problems with quoting characters that are special to the shell? for an explanation of that) and
• Escape the ERE metachars in the variable (see https://stackoverflow.com/questions/29613304/is-it-possible-to-escape-regex-metacharacters-reliably-with-sed which describes the same problem for sed, just apply the same solution using bash parameter substitution).

In the js example in your question if (/[0-9]+' and [0-9]+\$price/... - that regexp is identical to the one you'd store in a variable for bash except that in bash we use ' (or ") as the delimiter and so can't use ' (or ") in the string as-is while js is using / as the delimiter and so, I suspect, you couldn't use / in the string as-is and so the js regexp isn't actually any more literal than the bash regexp, it just uses different delimiters and doesn't need to be stored in a variable.

If you don't want to use a variable in bash, you can always just write a function to do the comparison:

$ cat tst.sh
#!/usr/bin/env bash

cmpr() { [[ "$1" =~ $2 ]]; }

text='The pizza is 2'\'' and 100$price' # The pizza is 2' and 100$price

if cmpr "$text" '[0-9]+'\'' and [0-9]+\$price'; then
    echo "this is what I prefer to have -- literal regex, like / /g in js. But this wont even compile"
fi

$ ./tst.sh
this is what I prefer to have -- literal regex, like / /g in js. But this wont even compile