You are but you won't save much as they're at a premium, save yourself a whole load of hassle and look into pre-builds, others will be along to agree in a while.

, I liked that.
I have a number of SMEs who buy white box servers from me, generally when they want a custom setup (ESXi compatible for example).
OP
The big advantage of buying off the shelf branded is that you get the warranty but you pay the price. The initial purchase of a server is usually pretty competitive but when you start adding ram and hard drives it starts mounting up pretty quickly. The recent HP M110G7 sale was a good example. The server comes with an extra 250GB hdd and an extra 2GB ram (4GB total) but if you buy more ram or storage from HP it will be very expensive. If you can live with the initial bundle deal or are not so bothered about the warranty then it is really a very good deal.
Last time I checked I could build 2 servers of the same spec compared to buying a Dell R210 with 32GB ECC (that was the killer), but that is unusual.
As for E3, i5 or i7, the E3 Xeon is a great CPU, the v2 is based on the Ivy Bridge die and the E3-1230v2 has hyperthreading (4 cores / 8 threads) for less cash than an i7. For motherboards, the Intel S1200BTLR or the Supermicro X9SCA / X9SCM tend to be very good. The intel board gives the basics with add-on options where as the Supermicro board have the basice or the -F models have the add-ons but it is one or the other. Note the S1200BTLR rear port config makes it difficult to fit in a 1U chassis (I know from trying).
For ram,
S1200BTLR Intel Certified;
- KVR13E9/8I (single 8GB)
- KVR13E9K2/16I (kit of 2x8GB)
For S1200BTLR or the Supermicro boards;
- KVR1333D3E9S/8G (single 8GB)
- KVR1333D3E9SK2/16G (kit of 2x8GB)
4GB sticks are also available.
The case specs seem to indicate a max of 13x 3.5" drives.
The boards above have 6x SATA so you would need a possible connectivity for up to 7 more drives.
The IBM M1015 is a good basic controller (based on the LSI 2008 chipset but usually needs flashing to the LSI bios to work in non IBM machines). The Intel RS2WC080 is essentially the same unit but branded as Intel. AFAIK this one does not need flashing but I have not tried it so cannot guarantee. The Intel card is usually a bit cheaper new. The advantage of the M1015 is that they can sometimes be easy to find on EBay for a fraction of the new price. Both these cards support RAID 0/1/10. Adding a feature key extends then to also include RAID 5/50 but without cache and battery backup (or non-volitile Flash based cache) this would not be recommended. For RAID 5/50 or up then something like the HP P410 with BBU or FBWC (Flash Based Write Cache) would be a good budget choice. These can also be found on EBay sometimes.
Most servers come with KVMoIP functionality so you can access from a remote location and have full control from booting up to accessing the BIOS etc. A monitor should not be required if you have this. The Supermicro '-F' versions of their boards do and the Intel board has an add-on to enable it.
To advise in a more targeted manner we would really need a lot more information;
What is the function of the server ?.
What is criticality of the server being up ?.
What sort of load is the server likely to experience (network, disk, cpu etc) ?.
What sort of budget ?.
Presumably you are putting the server in to fill a gap or to relieve resourcing issues. If it is the second (local server to cut down excessive file load times on shared storage for example) then you should have an idea of what sort of load will be put on the new server based on the people accessing and the load on the current server. Getting the stats will give a much higher chances of the server meeting expectations rather than overspeccing and wasting available capital or underspeccing and not resolving the issue.
Rb