Two hundred rupees are/is a lot of money.
It’s better to rephrase a bit —
Two hundred rupees are considered a lot of money.
Webpages with good explanations about this.
Basic rules about subject-verb agreement:
http://grammar.ccc.commnet.edu/grammar/sv_agr.htm
Also this:
...remember that the number (singular or plural) of the subject, not the predicate, determines the number of the verb.
from http://grammar.ccc.commnet.edu/grammar/plurals.htm#collective_nouns
The correct verb to use in this context is "is." Therefore, the sentence should be written as "Two hundred rupees is a lot of money." The verb "is" agrees with the subject "two hundred rupees," which is a singular noun phrase.
To determine whether "is" or "are" is the correct verb to use, you need to consider the subject of the sentence. In this case, "two hundred rupees" is treated as a collective unit, similar to saying "it is a lot of money." Even though "rupees" is plural, we can treat it as a single amount when discussing it as a sum of money, and therefore, use the singular verb "is" to agree with the collective noun.