I like the EFI systems. Cost wise, the new TBI EFI units are good when looking at 400-700 HP (NA) Engines. Under 400 HP, you can use smaller less expensive carbs, fuel pumps and such to keep costs down although you don't get the benefits of the EFI.
I haven't found a way to do EFI on the really cheap side yet. Setting up the EFI fuel system for me was the hard part. I originally used a sump kit in the stock tank and the external EFI pump, but later converter to an in-tank EFI pump. Really, if you have the ability to weld a sump kit on, you likely have the ability to modify a fuel tank for the in-tank pump. For many of our cars Tanks Inc and Spectra now offer EFI tanks making the conversion easier.
After setting up the fuel system, flush the fuel lines before connecting them to the EFI unit or fuel rail to make sure no trash is in the lines.
All my cars are running a return fuel line, and I connected the supply and return lines together with an old Summit Filter. Then ran the EFI pump for a minute to flush the lines. Reconnected the lines to the EFI, and inspected the filter element inside the Summit filter. I did find a small piece of rubber from the fuel line in the filter. If I did not flush the lines that debris could have gotten into an injector or regulator and cause problems that many would complain is the fault of the EFI, when it really was a install problem.
Anyhow, why did I mention the 400-700 HP (NA) range? That seems to be the range many are using the more expensive carbs and fuel pumps, and the cost difference between the higher end carbs/fuel pumps are near the same as the TBI EFI units and pumps. This also seems to be the focal point for many of the TBI EFI units. The 4150 flange TBI units are around 800 cfm, so the airflow might be a limiting factor with these when normally aspirated. The higher power numbers advertised with these units is that the injectors have the capability to supply fuel for more power in boosted combinations. Also, the larger injectors will work with E-85 but reduce the maximim HP of the rated system.
At 700+ HP (NA) you could use the Holley Super Sniper 4500, but the costs start getting to the point where port EFI might be a better option.