OK, got it.

The problem was manifold.

First, DragonChild correctly pointed out that the original array declaration should have been

$bases_tbls{'18p'} =  [ 't73', 't74', 't75', 't76', 't77' ];
[download]

Then, the line

$sql = 'SELECT respondent FROM';
[download]

was incorrectly placed. It should have been integrated into the loop, otherwise the line just got new items tacked onto it making a nonsensiscal sql command.

Finally, the right way to refer to the element was

$tbls{$price[$g]}[$i]
[download]

Thanks for the help, all. One of the few drawbacks of being an independent is the lack of other humans in the office to bounce problems off of.