brass diesel locomotives were originally started in Japan and later South Korea due to labor cost and other factors.Anjin ,Samhongsa,Katsuma,are the main builders of the locomotives the US companies that have them built are Overland models,Alco,Oriental,Hallmark,W&R,Challenger,Oriental,Sunset ,NWSL,Teneshodo,PFM,and Key.this just a small list to describe the origination and production process of these fine models.The brass locomotive are currently priced as follows diesels                                                                                                                                       Overland ( Anjin the builder) run from 245 to 800.00 in HO scale the lower prices are usually unpainted or tank drive without lights or decoders.The detail is about the same but the electrical aspect decoders and lights and sound is what adds to the price.The motors  are Mishima (japan) Bueller(german). The gp-series early has different  electrical pickup then later series.two to all truck pickup.Moving to Oscale the Overland locomotive will run from 550.00 to 2,000 same as with HO involving the decoder lights and unpainted plus details.these locomotives are big and are heavy and they are highly detailed.The same with HO as with Oscale the late 80's to 90's produced some of the best locomotives at the best price .The painted one's need a decoder unless they have been retrofitted and the quality of the brass can handle the additon of a decoder.The nscale from overland is new about 7 seven years or less for the current fleet of diesels coming from overland and this is good no old noise stuff in this scale its all new and runs about 200.00 to400.00 depending on the model .The oldest locomotives would be Hallmark and the large fleet of diesels they came out with in the 1980's.Key came out with some tunnel motors that had swinging trucks that had the steps attached to them Nscaler's know about these type's.Probably the best early brass Nscale model was the W&R FP45,F45 painted in Santa Fe if you can find one get it.Buying overland in any scale will return your money models of rare popular roads will go high.models of flooded roads example Union Pacific sd40-2 will still get your money but not as much as a DRGW SD40t-2 or Eire Lackawanna SDP45,SD45-2 .Some models are just costly to own you will pay to own one of the the DD35a,DD35b,DD40ax,SD40-2(snoot)Fast-forty, GP35 Union Pacific these are examples of Overland diesels .One key factor is Tank drive or Tower drive the Tower is the current  Overland drive system  and most realistic and the Tower drive represents the earlier overland  models up intill the late 70's and will cost about 100.00 less. Some seller's leave this important information out of the model description or they show you a picture of the type drive system .The picture being the best at knowing what your really looking  at buying .Oriental's Korean builder is Samhongsa  and they have not had a new model in year's  but the HO,O,Nscales were excellent running and well detailed models outside of not offering a cab interior the oriental detail and operating was equal to and better then the Overland of the time period the Oriental sd45,sd45-2 are some of the  best locomotive's and run around 270-400 on ebay .Oriental offers a wide selection of models and they are the very best of the Samhongsa offerings .Alco models is another former major player that Samhongsa built there models for and they were at one time in the early 70's the leader in brass model's.Alco model's are old but rugged and can be repowered and upgraded with detail's.The reason for the remotoring is alot of Alco models from that era  have split gears it happen with this builder.Between the two Alco and Oriental you can get anything that was offered to the class one railroads by the builders.Hallmark also used Samhongsa in HO and Nscale they also used KMT in HO but most of there stuff is very dated .As stated above there nscale is on ebay and around the hobby shop's if you need a type of locomotive.Challenger is the last of the Samhongsa builders so they are more expensive  then the above mentioned importers of Samhongsa about equal to Overland in cost.They had a good start but they are like Oriental have no new offering's so get them while you can.Sunset models offered a budget  brass line of both steam and diesel that was well built and detailed. about 150.-350.Sunset is alway's avalible you just have to look for what you need .Key is another long time importer of Samhongsa and expensive and not as good as Overland or Oriental involving Diesel's.Key is steam oriented in offerings and offer's some of the best.PFM offered a good tunnel motor in SP or DRGW six axle power that runs about 200-250 they also made there name with Steam offerings.PFM is offering a SW1500 so if you need a switcher check out PFM .Finally one thing about brass the older it is the more noise it will make unless it has been repowered.so when buying consider the following items;Importer,year built,type drive(Tank or Tower),Is this the only importer offering this or is there a newer version.Cost for item,painted or unpainted.lights and decoder.All of these item's can be a large factor in your purchase and enjoyment of a highly detailed brass locomotive .