Emission test failure, codes P0456, P0441 and P0340 on a 2003 Dodge Neon, are these inexpensive to get fixed?

You have a few different things coming up as these lights and codes. I'll list the code meaning below.
Did you mean the VSC light? VSC, Traction Control and ABS all refer to your braking system so get it fixed AS SOON AS POSSIBLE!
The '505' code refers to the air flow management system in the air intake manifold. The other codes refer to the EVAP system on the vehicle. This may seem a silly suggestion but check you fuel filler cap isn't loose, missing or the seal on the cap isn't damaged. The EVAP works as an air tight system and if it is leaking that is one of the most common causes, (and its a cheap repair).

P0441 = Evaporative Emission System Incorrect Purge Flow
P0455 = Evaporative Emission System Leak Detected (large leak)
P0456 = Evaporative Emission System Leak Detected (very small leak)
P0505 = Idle Air Control System

code p0446 refers to evaporative emission (EVAP) system--vent control--circuit malfunction===causes wiring--EVAP canister purge valve--ECM
Code p0441 is evap system--incorrect flow detected==causes --hose connections --intake leak--EVAP canister purge valve
replace the purge valve as it is common to both codes
dodge code p1400 is related to a problem EGR system

Google the Code

OBD2 Code PO441

P0441 Evaporative Emission Control System Incorrect Purge FlowOBD-II Trouble Code Technical Description

Evaporative Emission Control System Incorrect Purge Flow
What does that mean?

This indicates that a part of the EVAP control system is no longer functioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

EVAP emission canister purge is controlled by a valve which allows engine vacuum to pull stored fuel vapors from fuel tank into the engine to be burned, rather than be vented to atmosphere. A vacuum switch is used to detect when flow exists. If the PCM commands purge and sees that the switch is closed (indicating no detected purge flow) P0441 is set.
Symptoms

Likely, no symptoms will be discernible to the driver, other than the illuminated Check Engine Light.
Causes

A code P0441 could mean one or more of the following has happened:

• Bad vacuum switch
• Broken or damaged EVAP line or canister
• Open in PCM purge command circuit
• Open or short in Voltage feed circuit to Purge Solenoid
• Faulty purge solenoid
• Restriction in EVAP solenoid, line or canister
• Corrosion or resistance in purge connector
• Bad PCM

Possible Solutions

With a P0441 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

• Common Chrysler fix - Replace Leak Detection Pump / LDP
• Repair damaged EVAP lines or canister
• Repair open or short in voltage feed circuit to Purge Solenoid
• Repair open in PCM purge command circuit
• Replace purge Solenoid
• Replace vacuum switch
• Repair restriction in Evap line or canister or solenoid
• Repair resistance in purge connector
• Replace PCM

Other EVAP DTCs: P0440 - P0441 - P0442 - P0443 - P0446 - P0453 - P0455 - P0456

code p 0441 refers to evaporative emission (EVAP) system--- incorrect flow detected ===causes --hose connections---intake leak---EVAP canister purge valve
Take it to an accredited service center that has experience on your make of vehicle and get it repaired

P0456....Evaporative Emission Control System Leak Detected (very small leak)

P0440....Evaporative Emission Control System

p0456
Evaporative emission (EVAP) control system leak detected (very small leak)
p0440
Evaporative emission control system malfunction

Here you go
Read all about it
Looks like a fuel vapor leak and a missfire
http://www.obd-codes.com/p0456
http://www.obd-codes.com/p0441
http://www.obd-codes.com/p0303

Trouble Code: P0441 (2.0L L4 VIN C Auto)
EVAP Purge Flow Monitor Fault Print this code data Number of Trips to Set Code: 2
OBD II Monitor Type: CCM Details
Indicators: MIL Details

• EVAP Details

Trouble Code Conditions:
Engine at idle speed in closed loop for 200 seconds, BARO Sensor signal less than 8,000 feet, ECT Sensor more than 160ºF, no Low Fuel, MAP Sensor signal less than 23.7" Hg, and the PCM did not detect any purge flow through the EVAP system during this test.

Possible Causes:

• EVAP purge solenoid vacuum line loose, leaking or restricted
  
• EVAP purge solenoid stuck leaking, stuck open or stuck closed
  
• EVAP purge vacuum line to canister leaking or disconnected
  
• EVAP canister leaking, damaged or has failed
  

2005 Dodge Neon - All Configurations - P0441

p0456--emission control system leak(verysmall) leak, check all hoses to emission controls, cylinder 3 missfire detected. could be plugs, wires, or coil.this is code p0303,