High Resolution Objective Selection

I am building the beam split er style microscope and I am looking at selecting an objective. I understand that I want planar, infinity corrected. I am not knowledgeable enough to know whether the thickness of a microscope slide versus a cover slip will factor in my selection. I am building the microscope mostly because I am interested in what doors it will open up in terms of imagination and/or learning. I already have a compound microscope but the objectives are only planar and not infinity corrected. It would be nice if someone would discuss the selection of objectives like 'use what you got' versus "buy this first" then 'keep your eye out for this'. My first use will be a 'bucket list' of prepared slides. (which is what my other microscopes are doing) Next up might be observing microfluidic devices with fluorescence if I can manage it.
I am quite comfortable with the Raspberry PI so adding a syringe pump would be easy. I have a small CNC machine that I can make a micro fluiditic 'thingy' that I would like to be able to observe and track over time and temperature. Anyways, my objective is to be able waste my money equally and not just on a collection of microscope objectives that I don't use.

Oh well, I didn't get any responses. I did a little looking at the specs for inverted microscopes and decided that the working distance was an important feature of the objective. I found one of the existing high resolution builds using a 40X objective and PI V2 detector. It was helpful. I still have some parts to be printed and/or delivered. I will probably buy a metallurgical objective of 40x to 50X with a long working distance. most likely 40x Here are my choices: Standard LPL5X/0.1, LPL10X/0.25,LPL20X/0.4,LPL40X/0.65 LPL50X LPL80X INFINITY plan achromatic objective long lens for metallurgical microscope LPL5X work distance is:15mm LPL10X work distance is:18mm LPL20X work distance is:5.5mm LPL40X work distance is:3.89mm LPL50X work distance is:1.9mm LPL80X work distance is:0.8mm