It's likely to be more expensive than buying one, if one is emulating
the scanning receivers typically used.
Generally receivers, except for special cases which are not relevant here,
are amongst the most difficult pieces of amateur radio equipment to construct,
as much as anything because of the number of parts. A specialist receiver
would involve sourcing unusual components or making them oneself. (SSB
transceivers are more complex because the thransmit side is structurally
very similar to a receiver.)
> ALBERT EINSTEIN
I'd put this on the same line as the quote, so that it is not interpreted
as your name.