Is storing diluted (~1M) sulfuric acid, HCl, NaOH, etc. in plastic PET bottles a bad idea?
Here you can find thorough and clear instructions about using plastic bottles for acids and bases:

http://www.corning.com/lifesciences/emea/en/technical_resources/product_guid/bottles/material.aspx

A common rule is to not store strong acids and bases (like sulfuric and hydrochloric acids, and NaOH) in plastic bottles if you are not sure about the type of plastics.

Polystyrene bottles are OK for strong alkali.

Here is a PDF document on this topic:

http://csmedia2.corning.com/lifesciences/media/pdf/PSUG_Storage_Bottles_CLS_GL_025.pdf