I've been doing business with Inhouse Drugstore for about 5 years... I only had one problem with a missing shipment and they re-sent it immediately after I reported it at no charge.. They're a great company and hope they stick around. The drugs themselves come from various sources; their generic spiro comes from India and their Estrofem comes from Denmark, for instance... it should specify in the descriptions on their website.
About injection... I have to ask if there's a specific reason why you feel the need, specifically, to inject. I'm going to assume that you're doing this on your own (like I have the whole time.) I think that taking hormones under your tongue, by gel or patch are far safer than getting the right size syringe, dosage and precise placement of the injection. I think the risks here are greater than any perceived advantages over oral or topical administration. BTW, if I had to do it over again, I would have found a TS friendly endocrinologist to work with a long time ago.
......Just my two cents :-)