Where to get what parts/materials/BPO/BPCs
Short answer is Wormhole Space :)
Long answer is below
Polymers
Polymers are made in the Polymer Reactor Array which can only be anchored using a POS in 0.3 and below. A polymer reaction requires gas from Ladar sites in Wormhole space and normal mineable minerals.
Polymer reaction blueprints are seeded on the NPC market under Manufacture & Research / Reactions / Polymer Reactions
Making Polymers is on this page.
Components
A Hull and subsystem component is made up of Hybrid polymers and salvaged sleeper wrecks.
Component BPOs are available on the NPC market under Blueprints / Components / Hybrid Components.
Hull and Subsystem BPC
A Hull and Subsystem BPC is perhaps the hardest thing to get and make, the only way to get hold of hull/subsystem BPCs is to reverse engineer ancient relics found in WH space.
The decryptors and datacores for the reverse engineering come from sites within WH space and are also possible to get from failed reverse engineering attempts.
Ancient Relics
Ancient relics are gathered from magnetometric sites (and in some Radar sites) in WH space. Ancient relics are reverse engineered to get Hull and Subsystem BPCs.
Sleeper Loot
The loot that sleepers drop are like the nnth Tier Overseer's Personal Effects, in that they are tradeable to NPCs (Credron and Zainou are two) who will buy them.