The answser to this is going to depend completely on the budget available and the balance of tasks: You say you want to do WGS, SNP calling, transcriptome analysis, metagenome analysis and single cell RNA analysis, but these are very different tasks requiring different amounts of power, and even require different specs depending on which species. .
The system recommended by Prash could handle all thsoe tasks, in any organism, easily, but would be massively overkill if what you were really mostly doing was RNA-seq analysis, or bacterial genome analysis. Probably overkill for single cell RNAseq analysis.
I also think the costing is quite optimistic, at least by UK prices. The biggest tower I could spec out with Dell is 64Cores, 512Gb RAM, and 184TB disk, but that came in at over £100,000 (105 lakhs), although that mostly comes from the HDD. Without the HDD, its only £24,000 GBP (~25 lakhs INR).
Personally, I think that one single central server is not necessarily the best option. Much of the analysis can be done on relatively inexpensive PCs or workstations that will reliably run for many years without all the overhead that comes with running and sysadmining a server. Check whether your college maybe has some central computation servers for the heavy preprocessing like alignments, and then consider to do the actual hands-on analysis elsewhere. SOmeone needs to sysadmin the server if you buy it yourself, keep that in mind. Alternatively, depending on throughput, external cloud services might be economic for preprocessing tasks.
This is going to depend on scale. Probably easier to maintain 3-4 workstations used by research students, who can do some of the maintinance themselves. Competely different if its 100 undergrade: ensuring the proper functioning of a classroom of, say 30 workstations - making sure they all have exactly the same versions of everything, nothing is broken, everything is up to date, there are no security holes etc is a major undertaking.
We teach classes of (respectively) 600 students the basics of bioinformatics (alignment, annotation, quantification, assembly and SNP calling), similar numbers the basics of statis in R, 30ish students R-based downstream bioinformatics (DESeq2 etc) and 20ish students commandline, posix processing tools and python.
The best solutions we have come with for these are, respectively:
None of this infrastucture can deal with proper research level stuff. For the 10 or so students a year who need that, we use the university HPC cluster. I also have 1-2 workstations for long-term research students based in my lab, which is a small enough number I 'm happy to look after them myself.
Thank you very much for the valuable suggestions