As someone who makes his living developing software and inventory control systems I shall make a few comments.

1) I can't think of any good reasons why anyone would want to bar-code specimen boxes etc. Bar-codes in industry are typically used for similar items which make their way through a manufacturing process or for inventory applications where widgets are stored and you cannot put all the information on the box label that you might need. The curator of biological specimens better know where all his boxes are, no need to bar code the outside and then buy a scanner at $600-$800 a piece and all the connecting H/W to tell him what it is and where it is supposed to be.

2)Setting up a database in whatever way (one large file, many linked ones etc), defining all the fields, and writing the software is the easy part of making a system. Training, making sure everybody uses it (most systems are very unforgiving), making sure all the fields are given the right information, and interfacing the system with the H/W, - that is the difficult part. If it were only S/W, an experienced, good programmer/analyst could write you a loan and transaction management system using one of the modern development packages in weeks, assuming you could give him the specifications.

3)Remember also, that these modern packages need more megabytes every year, and by now also Pentiums to run properly. That involves considerable money. However if you do buy or develop in one of these packages you do get very useful options: like adding fields to your DB when you realize you forgot an important set of data without having to recompile everything, unlimited size text fields and pictures are handled just as easily as a fixed length ASKII field, and you can make your application look just like Windows!

The corner S/W store does not have an off-the-shelf the answer to your problems but there are many S/W developers who do.