The pricing of the Corrosive Burst weapon mod in the pfapg dataset (data/alpha/paizo/pathfinder_rpg/advanced_players_guide/pfapg_equipmods_weapons.lst) is wrong. The Corrosive Burst mod is split into a melee and ranged version and the ranged version has "COST:2000" instead of a "PLUS" for the cost. This doesn't match either of the two costs for that weapon mod in the APG; both of those are PLUSes.
The APG has a full-text description of Corrosive Burst which states the cost is a "+2 bonus". There are also two tables of costs in the APG for the weapon mods, one for melee and another for ranged. Paizo hasn't put it into the official APG errata yet, but it's clear the "+1 bonus" cost in the table for ranged weapon mods was a typo that just hasn't been corrected yet. Both in the table for the melee weapon mods, and in the full text describing Corrosive Burst, the price is clearly listed as "+2 bonus". Additionally, a price of "+2 bonus" is consistent with all the other elemental burst weapon modifiers from the core rulebook, and there's no rationale for the melee and ranged prices to differ for this weapon mod, particularly when they match for all other weapon modifiers which apply to both melee and ranged.
Corrosive Burst should either be changed to this (which matches all the element burst mods in the pf core):
Corrosive Burst KEY:CRRSVE_BRST TYPE:Ammunition.Weapon PLUS:2 VISIBLE:QUALIFY SOURCEPAGE.287 PREMULT:1,[PRETYPE:1,Enhancement],[PRETYPE:1,Ammunition.Weapon] SPROP:+1d6 acid damage, on a critical hit deals +%d10 additional acid damage|CRITMULT-1
Or (if you want to wait for it to be officially errata'd), the "COST:2000" on CRRSVE_BRST_R should be changed to "PLUS:1".
This is already fixed and will appear in the next release of 6.0 or you can see for yourself with the latest build of 6.01.1