Your description is confusing. A Colt AR-15A2 and an SP1 are two different rifles, though for all practical purposes the lower receiver is identical. It will have a large-hole forward pin rendering it incompatible with modern upper receivers unless an adapter pin is used. The "pencil" barrel is more likely a government profile and would be correct for an AR-15A2 Sporter. An SP-1 would come with an actual "pencil" barrel profile in 1/12" twist. The "bull" barrel may be an HBAR or an aftermarket. Do these barrels come attached to upper receivers or do you need to crank the barrel off the existing upper to replace it? That makes a difference in price.
A factory Colt AR-15A2 Sporter seems to run around the $1,200 mark on the EE. It's an older rifle that lacks the magazine well fence, has the large forward pin, and has no "rail estate" as I call it to placate the CoD fanboys so it's not as popular. However the name Colt carries that cachet that some folks seek so it retains a bit of a premium. Without knowing details about the two barrels it's hard to price out the package, but the rest of the tacticool stuff is only worth it if it interests you. Maybe call it an additional $200 in accessories.
If it comes with two uppers, conservatively add $400 to the price. If it's just a spare barrel, $150. Not that an upper receiver itself is worth $250 but unless you have the tools and proficiency you need to find someone to barrel that receiver for you.
To make a long story longer, $1500-1800 for that package would probably be fair. It would probably move quickly at $1400 and would be a steal at anything less.